It's a fast-paced Danmaku game, Z is for shooting, and X is to slow the bullets down so you can dodge easily.
The bullet patterns are really beautiful to watch, plus the cover is really beautiful, so it would rank high in Art for sure.
I am glad it doesn't have a try limit because I am really terrible at this type of game, it's good to know that suckers like me can also finish the game without any problem, other than dying a lot.
Overall, a great game to try if you like the Danmaku games, it's really challenging as well.