Most games have been mentioned here, especially the exclusives, but i'll mention them again
Exclusives:
- Ori and the Blind Forest
- Inside
- Rare Replay
- Sunset Overdrive
- Castle Crashers (really funny 2D RPG)
- Battleblock Theater (Platformer by the studio of Castle Crashers, 360, but compatible with the Xbox One)
Also you should keep your eyes open for ReCore, Pit People, We Happy Few and Cuphead.
If you like Strategy Games Halo Wars 1 & 2.
If you like Smash Bros. you should take a look at Rivals of Aether, that's a damn fine game.
Multiplat:
- Rogue Legacy (Rogue-Like)
- Shovel Knight (Jump 'n Run in the vein of Mega Man)
- Super Meat Boy (Platformer, 360, also compatible)
- The Witcher 3 (one of the best RPGs in years)
- Rocket League (Sports, but fun even if you don't like sports, like me)
- Life is Strange