Cuphead

Cuphead is an old-school shooting arcade game where the boss fights are a big part of the game. In addition to the final planet, every planet has a mausoleum. Within, the players battle poltergeists on their way toward a vase that provides them super if they complete the obstacle course successfully.

All of these monster battles and play levels occur on a different of the game's four separate worlds, with the game's finale confrontation with the Devil himself occurring on the fourth and ultimate planet. There are three difficulty levels available for each boss fight: easy, normal, and difficult.
To finish the game in normal mode, you have to vanquish each of the game's bosses, and after you do that, the expert mode will become available to you.