The original: http://gabrielecirulli.github.io/2048/
You will never be as great as Gabriele, because he is the original.
Doge: http://doge2048.com/
Such numbers, very combine.
Fibonacci: http://www.crazygames.com/game/2584-fibonacci
It’s harder, because you don’t match adjacent tiles, you have to go in the order of the Fibonacci sequence.
2(048): http://wegnerdesign.com/2048/
The numbers get smaller when you combine them. Easiest so far.
4D: http://huonw.github.io/2048-4D/
I’m not smart enough for this version.
Numberwang: http://louhuang.com/2048-numberwang/
Egad
Flappy: http://hczhcz.github.io/Flappy-2048/
It’s getting out of hand
Multiplayer: http://emils.github.io/2048-multiplayer/
Air2048: http://bennettfeely.com/air2048/
You just wave your hands in the air.
Large Hadron Collider: http://milrivel.github.io/LHC/
Combine particles to get the Higgs-Boson.
Kendra Savich, a friend from Radar Hill, has done a PokeVersion: http://alleyjack.github.io/Poke2048/
Definitely the best one yet.
Please add other versions in the comments.