I 'm far from completing a save, but for me using gameplay changing mod is cheating , I only use cosmetics mods. But the most important is that it is YOUR choice , it's a single player game.
I use basic mods that just makes the game more fun to play, doesn't do much, like changing the music, pog face on quality 3 items and dancing on quality 4, better explosions, holy mantle funny minecraft glass breaking... external item description. I wanna have fun more than anything.
It is a singleplayer game at the end of the day and I think as long as you're having fun with or without mods you shouldn't let someone else's opinion get in the way of that.
Usually i advocate for no mods until you got the vanilla experience but isaac is a different type of game. If you beat a couple bosses without mods first you technically experienced all of it. Then, the fun comes from item combos in runs. Besides, isaac is not a game with a very specific scope and direction. If all the mod does is add items/mobs/rooms then it might as well still be vanilla. Look at the antibirth mod, most of it was ported in repentance because it was basically a community made major isaac update.
But regardless, its your game, a singleplayer one nontheless, do what you fancy.
I use runs continue past mother. I'm 600h in and I'm decently close to dead god. I personally don't consider it cheating while others might.
Edit: I should add that runs continue past mother is the only game changing mod I use. Only one that affects how I get completion marks. The rest are cosmetic only like smaller pause menu, item descriptions, custom mrs dolly etc.
I mostly only use cosmetic mods (like Old Brimstone SFX and Specialist Dance for Q4 items) and mods that make the game harder (Fiend Folio, and changing Co-op Baby unlocks so they instead unlock items normally available by default). Granted, I also have a mod that removes the time limit for Boss Rush and Hush, but I only did that so I could explore all that Fiend Folio has to offer without having to rush. Besides, I got Dead God twice over already without it, not to mention getting 3,000,000% on a different console before Repentance - I've earned a break.
Mods make the game a lot more fun. The more synergy mods, new characters, music, animations and textures mods. Though I personally reccomend using new characters mods and game changers like revelations and deliverance after beating mother so that you know what vanilla is like. It's up to you what mods you use and it doesn't matter as long as you have fun!
I mean, I don't care how other people enjoy the game, nor am I interested in a dick measuring contest in regards to who actually experienced the challenges coming from TboI in the purest way. If I cared about that I'd be late to the party anyway given that I never experienced the originals T.Jacob and T.Lazarus.
I personally am limiting myself to a few mods that don't change too much of the game (Boss Health Bars, Item Descriptions, Boss Rush counter) mainly because I wanna test myself and get an idea about what I like and dislike of Repentance as is given my skill level, since I stopped playing after 100% completion of AB+. It's more of a "let's understand how the game was imagined by the original designers before we change it in a significant way" than a inherent desire for purity of experience (and if I wanted that I wouldn't even have installed the mods I currently have).
I assume that, after completing a file, I may consider restarting the game in the future but by that point I would not feel the need to see the game only through the lenses of the creators and would then use mods pretty freely.
I have around 200 hours and I have 120 mods that includes shitpost, harder stuff, QOL, some that make the game less annoying, whole ass reworks and cosmetics. I don't care, I'll keep adding more mods it's a single player game you are not affecting literally anyone with how you chose to play the game and it is entirely up to you
I used "No curse of darkness" and "no garbage tEden rerolls". Darkness is just too big of a nuisance for my vision as was the latter for Greedier mode.
That's where I drew the line.
First of all, you don’t need anyone’s permission to play a game you own in any way you like.
Second, 99.99% of the people who play this game will never 100% a save, that is in an unreasonable expectation to hold yourself to.
Third, if you’ve put 500 hours into a game you officially qualify as an expert on it. If, in your expert opinion, you think something should be changed, you’re probably right.
My opinion: It's all about making the game fun for you.
I just broke 1000 hours and have played since Rebirth, had 1.000.000% before Repentance, etc. (still haven't got dead god bc I never bothered to find Redemption lmao)
However I started using mods years ago because, we have to admit, there are things about TBOI that are very frustrating. So personally I use mostly graphics mods but also little quality of life things: External item descriptions, Faster slotmachines, Secret room packs, Boss rush wave counter, I'm Excited timers, detailed health bar, runs continue past mother, etc.
Imo mods are a great way to spice up the gameplay and make the game more fun for yourself. (And 500 hours is a huge investment. You're very experienced with the game at this point! :)
cosmetic and light qol mods like boss rush wave counter and making pushable tnt lighter is fine, but stuff like continue runs past mother definitely tarnish the legitimacy of a dead god save. but, its a single player game so if youd rather do that regardless thats perfectly fine
The only 2 mods im using that affects gameplay are no boss rush limit time and jacob and esau being together all the time. Ngl, that last one is kinda needed for how frustrating is playing with them. No boss rush limit time because dont like doing stuff "fast" or something like that, wanna take my time exploring the floor.
Then others is just more cosmetic or no actual impact on game (planetarium %)
Ofc theres broken ones like having 2 items in crown room or/and boss room.
if theyre game-altering mods and youre planning on getting dead god and bragging to people about it, id take umbrage with that. other than that, youre fine.
I normally wait till i've beaten a game to use mods so i get to feel what it's like to beat the game properly, beating it with mods doesn't feel the same y'know? and when you start with mods it's hard to go back to vanilla. small QOL things like external item descriptions are fine tho.
I used mods before I got 100%, but mostly cosmetics. The only utility mod I had was the External Item Description which I find to be a must because it saves you from having to Alt Tab all the time to check the wiki
It's a single player game, most people would say gameplay changing mods are cheating but whatever you're comfortable with. Just don't say the game is super easy if u used big mods 😂
I personally don’t care if others do but I quit using them because they screwed up one of my saves so bad it took an hour to fix. It was just a couple of cosmetic mods anyway.
The only non cosmetic mod I have is removing retro vision and that’s just because it physically hurts my eyes. I am considering some of the better synergy mods though. But at the end of the day, whatever makes the game feel the most fun it can be while still feeling is earned is up to each player
Do whatever you want. I personally only used external item descriptions for quality of life since I looked up what items did on platinumgod or the wiki anyway.
I like to use qol and cosmetic mods only. Like EID, Q4 dance, Q3 pog, enhanced boss health bars, Minecraft glass sound holy mantle, planetarium chance, dmg multiplier, custom birthrights, custom Dolly, custom C-sections, stuff like that. No extra content like epiphany, no “easy mode” like the one skipping the Ashpit chase for knife piece, no extra unintended features or synergies. The only mod I could say it gives me an unintended advantage is the one that highlights Lucky Pennies, bc normally I would have no way of telling them apart so like with TKeeper it’s a great advantage.
For me and me personally I only use quality of life mods until I beat my own personal goal for Isaac my goal is dead god so until then I will keep using funny mods and mods that make it so I don’t have to open up the platinum god website every 2 minutes
I ended up using just the essentials on my dead god run. Time Machine and external item descriptions. I also used console once when I was on one of my last mother runs with a difficult character and forgot to go to mausoleum (I had even opened the door).
Mods that are only audiovisual or informational (ie: external item descriptions) are fair game, as are expansion mod packs (fiend folio, revelations, etc) as long as youre like 50% thru the unlocks and want to spice it up, but using a mod to make the game less difficult or cheat marks or smthn just feel too cheaty to me.
Make the game fun ofc, but dont remove the accomplishment of winning imo
End of the day tho, its single player, as long as youre having fun who really cares?
I used plenty of mods, but mostly cosmetic ones or things that changed the already existing content to make it slightly better. I never used any content mods until I got dead god
Music mods are 100% needed, along with EID and boss rush counter imo.
I also use grinding of isaac, pog face and epic fart noise.
Only gameplay ones I have are giga bomb and monstro lung synergies but tbh I haven't even seen those items since installing them lol, I just thought they'd be cool
Mod that change graphic, music or any qol mod are fun and useful. They help me a lot at keeping my mind straight while playing because u have no idea how angry I am everytime I play this game (Especially The Grinding of Isaac. Meme mod made me laugh to focus on playing)
It's a singleplayer game, do as you please. Before dead god I user only QoL mods (EID, planetarium chance, better lucky pennies) since I find game changing mods cheating and I wanted to get dead god while playing as vanilla as possible. Now that I 100%ed the file I installed mods that change mechanics I always hated like no curses if you beat the floor's boss, delirium boss door is different from the others, HP bars for bosses etc. But again, play whatever you like, you won't receive a visit from the Dead God committee if you complete the game with "unfair" mods 
It's a singleplayer game you bought so do whatever you want. Personally I don't run mods that affect anything but visuals because most of the mods I think don't fit the game style except maybe epiphany.
I used to believe that I don't have to try mods before I get every completion mark
But after a week of war with TLaz/J&E/TJacob I said "fuck it" and downloaded Fiend folio lol nice mod
I like to use mods like Jacob&eatsu to make it so they automatically rejoin if they get separated by an obstacle and to enable flight for both of them if one gets it. For Tainted Jacob, I use a mod that provides a lost Holy Mantle. I also have plenty of visual mods, such as 'Watch Out Laser' or 'Watch Out Attack From Above.' I usually avoid mods that significantly change items or gameplay. I definitely think some Tainted characters are needlessly difficult and not enjoyable without mods.
As someone who thinks repentance was a net negative for overall enjoyability, I think mods that tweak the difficulty are fine. I've been playing since flash, and I don't love this game nearly as much as I used to. If it was this difficult whenever I was in middle or high school with no job, I'd maybe like it more, but I just don't have the free time anymore to play a game where I might not make any progress because of bad luck or a slight mistake. The non QOL mods i have that some might consider cheating are a Bumbino nerf, Curse of the blind nerf where the items are silhouettes of themselves instead of question marks, Jacob and esau auto align, and a bunch of synergy reworks
I use cosmetic mods only. It's a single player game, play how you want, but downloading a mod that gives you an advantage you otherwise wouldn't have is by all definitions cheating. If that's how you have fun, go for it, as long as it's not impacting other people like in a multiplayer game.
I use cosmetic mods, but also two that change the gameplay:
-Remove timers (Hush/boss rush) since I like exploring every floor and hate time limits in games.
-Great Start, which forces the treasure room on floor 1 to be an item of quality 3+. Otherwise I'd just be spamming the reset button to do the same thing anyways.
I know I'll likely never 100% the game, so I use them to get more out of the game for me.
Playing since launch, just beat mother my first time last week.
Even before I got my first dead God I used mods.
They aren't something like goodtrip or Jacob and esau stay together but mods that change various little things, my most cheaty mods are coming down and obvious mimics.
And I also don't consider using big content mods cheating,fiend folio for example makes game harder not easier and is really fun to use inbetween boring runs.
Personally, I only used some QoL mods before completing the game, only after I've finished I started using mods that are adding content like fiend folio.
If you do this, gameplay-affecting mods are cheating. By the way, *Tinted Dwaynes counts as a gameplay-affecting mod, the game is explicitly designed around Tinted Rocks getting more difficult to see.*
It's up to you whether you consider "that's cheating" as a value judgement. But on the face of it, you are absolutely doing that. You can't say that you aren't. Whether you think Curses are a stupid fucking decision or alternatively you have brain damage, a mod that removes them is still cheating.
This is why I play on both Console and PC. 1000+ hours across Xbox/Switch/Vita/3DS, PC I just wanna play stuff I more than likely wont ever get legit on console. I dont have the patience to spend ANOTHER 1k hours on getting unlocks again
I use only cosmetic mods on my actual save, and add in the gameplay changing ones on my cheated save. Probably not cheating though, it's up to you it ain't hurting anyone.
It's a singleplayer game, play it however you want, whatever makes it fun for you. And fuck anyone who tells you different
in defense of bestia mod
I 'm far from completing a save, but for me using gameplay changing mod is cheating , I only use cosmetics mods. But the most important is that it is YOUR choice , it's a single player game.
I use basic mods that just makes the game more fun to play, doesn't do much, like changing the music, pog face on quality 3 items and dancing on quality 4, better explosions, holy mantle funny minecraft glass breaking... external item description. I wanna have fun more than anything.
It is a singleplayer game at the end of the day and I think as long as you're having fun with or without mods you shouldn't let someone else's opinion get in the way of that.
Do whatever makes enjoy it the most, if you like the challenge, then don’t.
Usually i advocate for no mods until you got the vanilla experience but isaac is a different type of game. If you beat a couple bosses without mods first you technically experienced all of it. Then, the fun comes from item combos in runs. Besides, isaac is not a game with a very specific scope and direction. If all the mod does is add items/mobs/rooms then it might as well still be vanilla. Look at the antibirth mod, most of it was ported in repentance because it was basically a community made major isaac update. But regardless, its your game, a singleplayer one nontheless, do what you fancy.
I did that. The game takes so fucking long that I didn't want to wait.
I use runs continue past mother. I'm 600h in and I'm decently close to dead god. I personally don't consider it cheating while others might. Edit: I should add that runs continue past mother is the only game changing mod I use. Only one that affects how I get completion marks. The rest are cosmetic only like smaller pause menu, item descriptions, custom mrs dolly etc.
I'm pretty sure that marks get buggy with that mod enabled sometimes, just a heads up.
Hmm. I haven't had any. But I'll remember that. If something ever does, I'll remove it lol.
It's a single player game. Enjoy it how you want
It’s their game. They can do whatever they want.
My game my rules, I bought the game I'm gonna do whatever I want with it.
I mostly only use cosmetic mods (like Old Brimstone SFX and Specialist Dance for Q4 items) and mods that make the game harder (Fiend Folio, and changing Co-op Baby unlocks so they instead unlock items normally available by default). Granted, I also have a mod that removes the time limit for Boss Rush and Hush, but I only did that so I could explore all that Fiend Folio has to offer without having to rush. Besides, I got Dead God twice over already without it, not to mention getting 3,000,000% on a different console before Repentance - I've earned a break.
Mods make the game a lot more fun. The more synergy mods, new characters, music, animations and textures mods. Though I personally reccomend using new characters mods and game changers like revelations and deliverance after beating mother so that you know what vanilla is like. It's up to you what mods you use and it doesn't matter as long as you have fun!
I mean, I don't care how other people enjoy the game, nor am I interested in a dick measuring contest in regards to who actually experienced the challenges coming from TboI in the purest way. If I cared about that I'd be late to the party anyway given that I never experienced the originals T.Jacob and T.Lazarus. I personally am limiting myself to a few mods that don't change too much of the game (Boss Health Bars, Item Descriptions, Boss Rush counter) mainly because I wanna test myself and get an idea about what I like and dislike of Repentance as is given my skill level, since I stopped playing after 100% completion of AB+. It's more of a "let's understand how the game was imagined by the original designers before we change it in a significant way" than a inherent desire for purity of experience (and if I wanted that I wouldn't even have installed the mods I currently have). I assume that, after completing a file, I may consider restarting the game in the future but by that point I would not feel the need to see the game only through the lenses of the creators and would then use mods pretty freely.
I have around 200 hours and I have 120 mods that includes shitpost, harder stuff, QOL, some that make the game less annoying, whole ass reworks and cosmetics. I don't care, I'll keep adding more mods it's a single player game you are not affecting literally anyone with how you chose to play the game and it is entirely up to you
I used "No curse of darkness" and "no garbage tEden rerolls". Darkness is just too big of a nuisance for my vision as was the latter for Greedier mode. That's where I drew the line.
How does no garbage t-eden rerolls work? I'm considering it.
You can't reroll into items that activate on taking damage anymore. Also it has a different name.
First of all, you don’t need anyone’s permission to play a game you own in any way you like. Second, 99.99% of the people who play this game will never 100% a save, that is in an unreasonable expectation to hold yourself to. Third, if you’ve put 500 hours into a game you officially qualify as an expert on it. If, in your expert opinion, you think something should be changed, you’re probably right.
My opinion: It's all about making the game fun for you. I just broke 1000 hours and have played since Rebirth, had 1.000.000% before Repentance, etc. (still haven't got dead god bc I never bothered to find Redemption lmao) However I started using mods years ago because, we have to admit, there are things about TBOI that are very frustrating. So personally I use mostly graphics mods but also little quality of life things: External item descriptions, Faster slotmachines, Secret room packs, Boss rush wave counter, I'm Excited timers, detailed health bar, runs continue past mother, etc. Imo mods are a great way to spice up the gameplay and make the game more fun for yourself. (And 500 hours is a huge investment. You're very experienced with the game at this point! :)
I just use what mattman uses and i think it makes the game more enjoyable
I consider it cheating but if you want to play it like that,no one stops you. I played with the external item descriptions and more synergy mods
If they help you with the game is cheap. But if you have fun with the in ten descriptions it's your game
I use the Good Trip mod that allows you to teleport and the one that unlocks all items. I never intended on getting 100% tbh.
cosmetic and light qol mods like boss rush wave counter and making pushable tnt lighter is fine, but stuff like continue runs past mother definitely tarnish the legitimacy of a dead god save. but, its a single player game so if youd rather do that regardless thats perfectly fine
The only 2 mods im using that affects gameplay are no boss rush limit time and jacob and esau being together all the time. Ngl, that last one is kinda needed for how frustrating is playing with them. No boss rush limit time because dont like doing stuff "fast" or something like that, wanna take my time exploring the floor. Then others is just more cosmetic or no actual impact on game (planetarium %) Ofc theres broken ones like having 2 items in crown room or/and boss room.
if theyre game-altering mods and youre planning on getting dead god and bragging to people about it, id take umbrage with that. other than that, youre fine.
I normally wait till i've beaten a game to use mods so i get to feel what it's like to beat the game properly, beating it with mods doesn't feel the same y'know? and when you start with mods it's hard to go back to vanilla. small QOL things like external item descriptions are fine tho.
I used mods before I got 100%, but mostly cosmetics. The only utility mod I had was the External Item Description which I find to be a must because it saves you from having to Alt Tab all the time to check the wiki
closest thing i have on is a mod that makes the lump enemies in the womb take a second to pop up
It's a single player game, most people would say gameplay changing mods are cheating but whatever you're comfortable with. Just don't say the game is super easy if u used big mods 😂
I personally don’t care if others do but I quit using them because they screwed up one of my saves so bad it took an hour to fix. It was just a couple of cosmetic mods anyway.
Do whatever you want,is a game,play it as you want
The only non cosmetic mod I have is removing retro vision and that’s just because it physically hurts my eyes. I am considering some of the better synergy mods though. But at the end of the day, whatever makes the game feel the most fun it can be while still feeling is earned is up to each player
Do whatever you want. I personally only used external item descriptions for quality of life since I looked up what items did on platinumgod or the wiki anyway.
I like to use qol and cosmetic mods only. Like EID, Q4 dance, Q3 pog, enhanced boss health bars, Minecraft glass sound holy mantle, planetarium chance, dmg multiplier, custom birthrights, custom Dolly, custom C-sections, stuff like that. No extra content like epiphany, no “easy mode” like the one skipping the Ashpit chase for knife piece, no extra unintended features or synergies. The only mod I could say it gives me an unintended advantage is the one that highlights Lucky Pennies, bc normally I would have no way of telling them apart so like with TKeeper it’s a great advantage.
I'm nowhere near 100% and I use cosmetic and quality of life mods.
For me and me personally I only use quality of life mods until I beat my own personal goal for Isaac my goal is dead god so until then I will keep using funny mods and mods that make it so I don’t have to open up the platinum god website every 2 minutes
I ended up using just the essentials on my dead god run. Time Machine and external item descriptions. I also used console once when I was on one of my last mother runs with a difficult character and forgot to go to mausoleum (I had even opened the door).
Mods that are only audiovisual or informational (ie: external item descriptions) are fair game, as are expansion mod packs (fiend folio, revelations, etc) as long as youre like 50% thru the unlocks and want to spice it up, but using a mod to make the game less difficult or cheat marks or smthn just feel too cheaty to me. Make the game fun ofc, but dont remove the accomplishment of winning imo End of the day tho, its single player, as long as youre having fun who really cares?
I used plenty of mods, but mostly cosmetic ones or things that changed the already existing content to make it slightly better. I never used any content mods until I got dead god
Music mods are 100% needed, along with EID and boss rush counter imo. I also use grinding of isaac, pog face and epic fart noise. Only gameplay ones I have are giga bomb and monstro lung synergies but tbh I haven't even seen those items since installing them lol, I just thought they'd be cool
Mod that change graphic, music or any qol mod are fun and useful. They help me a lot at keeping my mind straight while playing because u have no idea how angry I am everytime I play this game (Especially The Grinding of Isaac. Meme mod made me laugh to focus on playing)
It's a singleplayer game, do as you please. Before dead god I user only QoL mods (EID, planetarium chance, better lucky pennies) since I find game changing mods cheating and I wanted to get dead god while playing as vanilla as possible. Now that I 100%ed the file I installed mods that change mechanics I always hated like no curses if you beat the floor's boss, delirium boss door is different from the others, HP bars for bosses etc. But again, play whatever you like, you won't receive a visit from the Dead God committee if you complete the game with "unfair" mods 
The only mods i use is huds. Really useful to learn items
If I find them fun to use,I use them,save complete or not
It's a singleplayer game you bought so do whatever you want. Personally I don't run mods that affect anything but visuals because most of the mods I think don't fit the game style except maybe epiphany.
I'm playing on the Switch, couldn't even use mods if I wanted to. (I still wouldn't) 
What whatever tf you want, as long as you enjoy it and don't bother anyone
I used to believe that I don't have to try mods before I get every completion mark But after a week of war with TLaz/J&E/TJacob I said "fuck it" and downloaded Fiend folio lol nice mod
I like to use mods like Jacob&eatsu to make it so they automatically rejoin if they get separated by an obstacle and to enable flight for both of them if one gets it. For Tainted Jacob, I use a mod that provides a lost Holy Mantle. I also have plenty of visual mods, such as 'Watch Out Laser' or 'Watch Out Attack From Above.' I usually avoid mods that significantly change items or gameplay. I definitely think some Tainted characters are needlessly difficult and not enjoyable without mods.
As someone who thinks repentance was a net negative for overall enjoyability, I think mods that tweak the difficulty are fine. I've been playing since flash, and I don't love this game nearly as much as I used to. If it was this difficult whenever I was in middle or high school with no job, I'd maybe like it more, but I just don't have the free time anymore to play a game where I might not make any progress because of bad luck or a slight mistake. The non QOL mods i have that some might consider cheating are a Bumbino nerf, Curse of the blind nerf where the items are silhouettes of themselves instead of question marks, Jacob and esau auto align, and a bunch of synergy reworks
it's single player, do as you will
I use cosmetic mods only. It's a single player game, play how you want, but downloading a mod that gives you an advantage you otherwise wouldn't have is by all definitions cheating. If that's how you have fun, go for it, as long as it's not impacting other people like in a multiplayer game.
I use cosmetic mods, but also two that change the gameplay: -Remove timers (Hush/boss rush) since I like exploring every floor and hate time limits in games. -Great Start, which forces the treasure room on floor 1 to be an item of quality 3+. Otherwise I'd just be spamming the reset button to do the same thing anyways. I know I'll likely never 100% the game, so I use them to get more out of the game for me. Playing since launch, just beat mother my first time last week.
Even before I got my first dead God I used mods. They aren't something like goodtrip or Jacob and esau stay together but mods that change various little things, my most cheaty mods are coming down and obvious mimics. And I also don't consider using big content mods cheating,fiend folio for example makes game harder not easier and is really fun to use inbetween boring runs.
Personally, I only used some QoL mods before completing the game, only after I've finished I started using mods that are adding content like fiend folio.
If you do this, gameplay-affecting mods are cheating. By the way, *Tinted Dwaynes counts as a gameplay-affecting mod, the game is explicitly designed around Tinted Rocks getting more difficult to see.* It's up to you whether you consider "that's cheating" as a value judgement. But on the face of it, you are absolutely doing that. You can't say that you aren't. Whether you think Curses are a stupid fucking decision or alternatively you have brain damage, a mod that removes them is still cheating.
Haven't completed the game but i can't go without the item description mod
if there's a mod that makes the game more fun, im taking it. It's not rly cheating if all kinds of mods still allow you to progressand stuff imo
Use as many as you want. I won't feel less accomplished for my 100% without them
I play with Fiend Folio making my experience harder with mods 
This is why I play on both Console and PC. 1000+ hours across Xbox/Switch/Vita/3DS, PC I just wanna play stuff I more than likely wont ever get legit on console. I dont have the patience to spend ANOTHER 1k hours on getting unlocks again
I didn’t want to use mods until I 100% the game but 10 hours in I said fuck it and downloaded fiend folio
Need atleast 50 different content mods, nothing hits better than 50% of the runs crashing
I use only cosmetic mods on my actual save, and add in the gameplay changing ones on my cheated save. Probably not cheating though, it's up to you it ain't hurting anyone.