i really enjoy the concept, and could see myself chewing through a full release! a story mode or arcade mode of sorts would be a lot of fun. i think of something like puyo puyo sun's story/arcade mode(easy/medium/hard stories) and it would be a great fit for this.
the number of items i can buy at the shop is a bit overwhelming, though. maybe you could unlock a few options at a time to allow people to onboard?