There's a nifty iOS game called Threes, in which you slide numbered tiles around on a board and combine them into multiples of three. As I played it for the first time a couple weeks ago, it occurred to me that it's conceptually very similar to Triple Town, in which you combine items in sets of three to grow them into bigger items, except that Triple Town involves various kinds of plants and buildings and such (and wandering bears), whereas the more abstract Threes is just pure numbers.
And now there are other related games. Another company created a game called 1024!, which uses powers of two instead of powers of three; it explicitly bills itself as a free (for now, and ad-supported) alternative to Threes (which costs $2 at the moment), and its look is very similar to that of Threes. It comes across to me as an opportunistic way to capitalize on the success of Threes, so I'm pleased to report that someone else has created a free in-browser variant called 2048.
All of these games have slightly different gameplay, but the general idea is the same for all of them. Pretty cool, and fun.