2048 was too easy : welcome 4096

I beat it on my first try, using my strategy (and far too much practice) from 2048. However, when I play 2048, I have the board completely full at some point in maybe ~50% of games won, so I'd guess this version is winnable roughly half as often, since an extra spot is taken up for the whole second half of the game by the 2048 tile.