I greatly enjoyed this game when I first played it 6 years ago. I got into it a second time recently, and got super obsessed with trying to figure out what was supposed to be the true ending. I want to write my findings out for anybody who's interested in this game - will try to make accessible to new players, no major spoilers ahead.
The actual endings in the game are:
1 bad end for War(Blue) - You can unlock her seal without ending the game.
1 bad end and 1 good end for each of Famine(Purple) and Death(Pink).
1 bad, 1 very bad, and 1 good end for Pestilence(Green)
The game advertises 9 endings, and I assume the 9th ending is meant to be the true ending. however, there seems to be no dialogue for the true ending in the game files.
It's explained if you do the right thing at the right time in the tutorial, but basically the "seals" in game are unlocked (and give special abilities for future runs) by getting the good ending for a character. Each ending is largely independant of the others. War and Pestilence (AKA Blue and Green) seem to play well together - I recommend doing them at the same time if going for the good ending for both, but you don't have to. Famine and Death seem to be independent of one another, and require 2 different runs.
Another thing I couldn't figure out was the impact of the THIS. IS BULLSHIT segments (AKA moments of blantant racism). Primarily, it seems like they contribute to Pestilence's story. I'm not sure if you get anything for finding all of them, but the game has a counter, which indicates that you're supposed to.
My hunch (based on the fact that the pestilence arc has by FAR the most content, and also contains an action that can only be taken once you've beaten it once) is that the pestilence arc is also supposed to host the true ending. However, since the true ending was cut...there's no way to know!!
I have gotten very very obsessed with this game over the past two weeks, and, on a personal level, I both love it and really wish it were more complete in a lot of ways. Thank you so much to the creators for making such an awesome story and for all of the great writing and art that went into this. If you have not played it (and are still here somehow) I highly recommend playing the game and at least completing the pestilence storyline. it was very meaningful.