There's a saying that a dancing bear is interesting not because it dances well, but because it dances at all.

This game is a dancing bear.

It's legitimately impressive that it's even possible, yes, and doubly so that some madlad actually pulled it off, but as a game it's... not actually very fun, I'm afraid.

If you have enough technical literacy to understand why writing a game in pure HTML/CSS is utterly insane it's worth checking out because, seriously, lol what. If you don't fully understand the difference between a website and an app and don't know what CSS is, don't bother, you won't get it.