Spoiler! Ending discussion. Where did it all got wrong?

[Imōtaru Bureikā]

So. I've got the bad ending (red main menu) it seems. I don't understand what the criteria and how many endings there are. I never sold out Stan, yet he was still seemingly killed I guess? I don't mad or anything, just wanna know where exactly did I go wrong in story choices.

[Gias]

Stan never died for me so must be dialogue choice.
One that comes to mind is when IO asks you who your helper is, you can choose " dont know anyone but stan" or name your exclusive helper which looks like a choice between either your helper or stan dying as a prime suspect. I choose exlusive helper and had later a scene where she got abducted mid talk while stan lived.

As for bad ending the game shows you a "first acers to finish" celebration so you are the cause their project is done when you complete all quests for IO. Orb tells you collect all phenomena and game says you cant collect phenomena anymore on that save. Looks overall like a good ending requires getting them all.

[Seinekar]

That sucks, because then you have to replay the whole game (albeit with inherit) to get a good ending. And going through the full story and sidequests again seems tedious.

I guess thing is to just avoid the last mind upgrade until all phenomena or sidequest is completed.