Ikaruga
Although it may not be immediately obvious Cuphead shares a lot in common with bullet hell games, especially in its flying boss battles. The flying battles of Cuphead area all about dodging a wealth of projectiles and enemies that get thrown at you, while trying to slip in your own shots where you can. That’s exactly what bullet hell games like Ikaruga are about, and they just so happen to be incredibly hard too. You play as a pilot named Shinra, who battles an enemy nation with a fighter named Ikaruga that can switch between two polarities, black and white.
This mechanic is what the game revolves around, and enemies are marked with either a black or a white color. During each stage you’ll need to constantly be switching between the two polarities in order to take enemies out, and keep yourself alive. Ikarugao is played from a top down perspective, instead of a side view like Cuphead, but the same idea applies in dodging projectiles and taking down enemies as quickly as possible.