Megaman X - Probably the best Action Platformer ever, it teaches you all the basics of the genre through gameplay alone.

Metal Slug 2 - Cuphead too hard for you? Then give this good ol' classic a shot! It has simple yet fun mechanics and you can go as trigger happy as you want. And don't feel bad if you play on Free Play Mode, what matters is that you have fun!

Gran Turismo (PSP) - If you want to get into the series (or into Racing Simulators in general) this is probably your best bet, you have all stages available from the beginning and very little customization, but you can feel the progressiveness of the game as you buy more powerful cars and unlock higher difficulties.

Grand Theft Auto III - This game can be really hard at times (no swimming, only 3 safehouses, cars are really fragile, etc.) But once you understand the mechanics of the game and you start getting better, the rest of the series is a piece of cake. (Also, i loved the freedom you had when performing most missions in this game, it makes sense that later titles restricted you due to being more "story oriented", but GTA V's missions really just feel like going through film setpieces that is boring :/)