Seeds are 2, 3, 5 and 7 with equivalent probability (in regards to the random results, I'm not talking about the JS random generator quality here).
You can join number if they one of them can be divided by the other, in this case their values will be summed and the merge tile will contains the result.
25th march 2014: New token for score to avoid collision with FIB scores, sorry for resetting you high scores :/
How to play: Use your arrow keys to move the tiles. When two tiles which can devide each other touch, they merge into one, adding their values!