There is so many of them, but I'll try my best to put it.
1. Terraria
I think it's quite normal one, since all I do is... hours of mining, grinding on event, and brutally squashed by some enemies.
2. Phantasy Star Portable 2 Infinity
The game is really good. The thing that I played this until I forgot when to sleep is, completing every single one of the stages in underleveled state (sometimes).
3. Sonic 3 & Knuckles
As someone who's been a fan of Sonic since early age, it took me quite a long time to notice that Sonic 3 and Sonic & Knuckles are connected each other. It took me quite a long time to complete the game (with every emeralds collected in every characters).
4. Zero Tolerance
The game is quite hard, and it took me more time to adapting myself with first-person shooter game, since I feel like playing horror game at first.
These will be all, I think. I'll add more if needed.