Gabriel Knight's ending was a bit tough. Once you find the cult you can't make any mistakes or it's game over. So cool that Tim Curry & Mark Hamill did voicework for this!
In PQ4 if you didn’t decide to have your inventory open during a courtroom scene, hovering over your pistol, you won’t have time to react when someone lunges at you with a knife. That game may have had issues.
Getting to Leisure Suit Larry 3's fourth wall breaking ending is a little difficult with tips alone! Though not harder than taking down Dr John without Mosely's help. Nice kick on Grace's part, but the man's made of iron.