This game is so good.
The story is absolutely fantastic, it's very complex and told in an EXTREMELY interesting and unique way but still makes perfect sense. Because of the nature of the presentation, plot revelations can be found in completely different orders depending on the player's choice. I've never seen anything quite like it, and it's really amazing.
The gameplay is also really fun and pretty unique, although not as unique as the story. It's a fusion of tower defense and trpg with a focus on customization. The enemies are pretty standard but still lead to fun situations that force you to improvise.
The game definitely isn't for everyone. You're essentially playing a normal game bundled together with a visual novel that you swap between. They feel rather disconnected, which is definitely intentional but some people might not be a fan of. It's also a bit too anime for my tastes (although the plot and characters more than make up for it). Also, it's a small issue but there's one or two characters who feel a little bit underdeveloped considering their plot significance, even if they only feel underdeveloped because of how good everyone else is. All of these issues don't really matter though, especially considering how amazing it is that this game works at all.