Recs.
Updated
Cuphead is a run and gun action game, consisting mainly of boss fights. It's inspired by cartoons from the 1930's, and the visuals and music are created using the same methods as cartoons from that era. The gameplay is very active and fast-paced, so expect to die a lot.
SpecsUpdate
Pros
Pro Creative and challenging
The gameplay is centered around defeating bosses, each boss has unique abilities and varying difficulty. Often there is a lot happening on the screen at once, which can be disorienting- this is part of the charm and challenge. You really need to be quick and pay attention to your surroundings at all times, otherwise you will die a lot more (though you'll probably die plenty of times anyway). The sequence of attacks from the bosses changes around at random, so there's no way you can be 100% sure of what will happen next even after you've played against a boss a few times.
Pro Excellent co-op
While it can be overly frustrating when you're playing alone, Cuphead also has local co-op for two players, making your adventure easier but a lot more enjoyable. The boss fights become shorter because together you deal more damage, you don't take needless hits because you can cover more blind spots, and you can even resurrect the other player by touching their ghost if you die. This way you still get the satisfaction of a challenging fight, but it won't be as disappointing if you fail. Even if you're not into challenging games, co-op can be a way to enjoy Cuphead.
Cons
Con Hard as nails
Cuphead mostly consists of multi-phase boss battles that may take you a lot of tries to beat. These involve a fair amount of trial and error, requiring you to gradually and perfectly memorize each boss' patterns, abilities, and timings. This becomes harder because you die in several hits, so even the tiniest mistakes are costly in the long run. It can be really frustrating if you die right before beating a boss since you have to get through the entire fight again. If you're expecting to simply enjoy the old timey visuals and music, you might get severely disappointed.
Con Doesn't have anything new in terms of gameplay
If you're expecting some innovative mechanics or cutting-edge gameplay, you might be disappointed. There are no strange physics, no unique moves, and even the story is just a premise for fighting a lot of weird creatures in a row. However, the game doesn't promise to be anything it's not, and if you have reasonable expectations, you'll probably have a lot of fun.