how to play
- swipe. every tile slides as far as it can.
- two equal primes that meet make the next prime: 2 and 2 make 3, 3 and 3 make 5, 5 and 5 make 7.
- after each swipe a new tile slides in from the edge you swiped away from. the small tile under next shows which one.
- drag slowly to peek at a move. let go early to take it back.
- the game ends when no swipe can change the board. there is no clock.
on a keyboard, the arrow keys work too.
scoring: each tile is built from twos. 3 holds two of them, 5 holds four, 7 holds eight, and 37 holds 2,048. a merge scores the twos it gathers.