Copied code from https://github.com/fullstackio/ng2048
Implemented basic puzzle15's gameplay
Removed unused 2048 mechanics
Added random generation
Use spacebar to start a new game
Improved random generation
Added chronometer and highscore
Prevented random generator from generating identity
Added win condition
Changed spacebar behaviour
Bugfix: highscore was reset if solved in less than 1s
Improved timer behaviour