I purposefully ruled out hexagons/curses to have some novelty in the mix but the final theme did end up being bit of a stretch. I was working on a fire mechanic for merge where you could knock a flame source into a pile and make it explode but the performance suffered a bit. I like your one shot suggestion, maybe another mode down the line.
What browser/os? That sounds like a failure pretty early on...I may have gotten bitten from some experimentation with ES3 that I forgot to turn off :(. I'll take that out after the rating ends since I'm not currently using it for anything.
Basic physics are the merging of multiple vectors in whatever coordinate space. It's a loose theme interpretation and an excuse to experiment with Box3D mostly.
