Currently I’m working on Jump King and SFV but probably out of all the games I’ve played the hardest was Injustice which I just recently finally got after years of wanting it.
Wolfenstein II. The Mein Leben trophy is absolutely brutal. It's horrible to do a 3+ hour run without saving and to make 1 mistake and have to start over. Some fighting games have crazy platinum requirements, but I'd rather practice learning a combo string over and over for a 2-3 minute combo vs permadeath with no saves.