>>6392106RPG/bullet hell with a large focus on story/characters. Not terribly difficult (except for the Genocide run). Lots of little things hidden all over the place to get unique reactions out of characters, so it's fun to experiment.
The gameplay is pretty unique, and fun, albeit fairly simple at times. The biggest advertising point of the game is that you don't have to kill any characters or enemies, and instead, you can Act certain ways to pacify them. Certain actions can give unique reactions, make the battle easier, or even help you out in later battles.
The characters are all really great, and while the game has a lot of focus on humor, it can get pretty emotional. It can even be fairly ominous at times.
Lastly, the music is fucking incredible. The creator of the game was a major music creator for Homestuck; and while that's a bit of a red flag, there is literally nothing homestuck/tumblr-related in the game (despite what /v/ likes to think). Normally I don't really care about music in video games, but in this case it really adds to the experience.
All in all, it's definitely worth the buy, or at least pirating and checking out. There aren't many things I can say are wrong with the game; my only complaints are that most of the game is pretty easy (there is a hard mode, but the game creator is lazy as shit and didn't finish it past the very first part of the game; he said he might finish it someday but I won't hold my breath), and there really aren't many puzzles in the game at all (despite what the tutorial makes it out to be).
tl;dr I'd give it a 9/10, definitely worth checking out.