Threes! has such great personality. It's so much more than 2048, and it's well worth the buck or so it costs. I hope it's had an uptick since the 2048 craze.
The chain roughly goes: Threes! was released in February. A near-clone called 1024! came out on iOS at the start of March. 2048 acknowledges the debt to 1024!, and the first commits to the git repository were in the first week of March.
Once the source code was available, tiny variations became much easier to fork, and we got a cambrian explosion mostly descending from 2048. (There was another 2048 as a parallel development, with significantly different visual style. Not sure where it falls in the timeline.)