Blasphemous
The first one. I beat it once before after it launched, but later on they added DLC that included a true ending, so I figured before I play 2 I should go back and get that. Ho-ly fuck is it cryptic. If you don't use a guide like I did I don't know how you'd ever be expected to figure it out on your own. In fact, even with a guide I ended up having to play the game twice because I accidentally fought a boss too early and locked myself out of the true ending. Yeah, I was pissed. It's still a good game but while playing it I was reminded of some very aggravating things about it, such as the instant death spikes, flask upgrades decreasing how many you can carry, and needing to spend 20,000 tears at the donation box in order to be able to teleport between shrines. Does it ruin the game? No, I wouldn't say so, but it did make it less fun. I'm done now, though, so I can finally play Blasphemous II and see what the devs learned from the first game. I'm excited.