The main mechanic of bouncing the shells off the wall is really fun. The first few runs I had no idea what was happening but I had fun just pushing the shell around. Once I figured out how to actually get the gold it was a lot more fun, since I could actually plan the best route.
Having to work around the other player is pretty interesting, but you can get really screwed over. I was robbed of my best run :(
This was a lot of fun, I think you could really push this concept further