Hello Finduses,
Thanks for your feedback!
I put the instructions on game's page, but basically the numbers within the blue spots inform how many fake spots are around that box. The next connected blue spot can only be one of adjacent spots (up, down, left, right) and not diagonal. However it doesn't mean that a diagonal spot is not also connected to another one.
TIP: Generally if you also take account of the number of previous blue spots, you can make a more confident guess. ;)
Thanks for playing!
Cheers!