Some important differences: * the first step is explicitly 1 + 2 = 3 (which you mentioned), 1+1 and 2+2 do NOT add * You move all tiles a single space at once, rather than 'to the edge'. Note tiles only merge when they push together, so an edge or other cards restricting their movement. This is a side effect design decision of single space moving. I do not know if two pairs will merge, e.g. will 3 + 3 + 6 + 6 leave 6 + 12? I suspect it will, but I haven't seen it. * Numbers 1 and 2 both spawn, and there is a 'next number' indicator, although placement still appears random. (A 3 spawned in the tutorial, but I think that was a special case)

Overall this leads to a very different feel to the game.

Anything else I missed?

3 + 3 + 6 + 6 can't make 6 + 12 because the tiles can only move one step. The ones near the edge will merge first (depending with way you push it).

There's Even on Android (https://play.google.com/store/apps/details?id=com.prasio.eve...) which uses powers of 2. It's really addictive!

Thx. I have just bought it, $3. Its almost the same idea, with slightly different mechanics. The 2048 animations are much "better" imho.

Yeah, after Threes, 2048 felt a little easier, though. Enjoy Threes, I already thing it was well worth it: real moment killer without being excessively mindless