To be honest, I think you're completely missing the point. The game, Chromashift, is not a serious attempt to make a quality game. It was an opportunity to try building a (somewhat) complex system with the IDE they've been working on. Along the way, they took some inspiration from CES, and brought it back into LightTable. And yes, CES can be used to create games with relatively good performance. Take a look at Replica Island [1], an open-source 2D side scroller for Android that runs well on the low-powered Android devices that came out 2-3 years ago.

Anyways, the main point: what does the fact that Clojure isn't a great language for building games have to do with this post?

[1]: http://replicaisland.blogspot.com/