So I just wanted to ask, is there like a guide for the achievements? I still have one I didn't achieve and it is shown as a secret in steam. I finished the "???" part, so im clueless right now. Any help?
After completing the game, you get a small extra by pressing the new ???? option. Here they will tell you about getting all hearts with all characters, and if you do and reach the end of the game again, there's a short extra scene. After that visit the ????? and you get the achievement.
Summary: get all hearts and complete the game again.