My first pick is Hollow Knight, for $15 you get a game that could have come out as a follow up to Super Metroid and I would have been delighted with it. You're playing a bug wielding a nail and exploring a vast complex of underground caverns. This game is pretty challenging and provides many hours of game play.

Just Cause 3, this game is pure fun! It does get a bit repetitive clearing bases but only if you clear them the same way each time. You can drive sports cars, airplanes, jet packs, boats, and blow everything up in spectacular fashion. Many hours of game play and tons of shit to unlock.

Binding of Isaac: Rebirth... Now here's a game that gives value for money. In order to unlock everything you have to play the game countless times. Its a rogue-like dungeon crawler with some bullet hell moments thrown in with a Zelda lttp art style if the artists died and went to hell. If you like a challenge here it is. I much prefer rebirth to afterbirth by the way.