From just trying things randomly, I think the objective is to get each numbered square to 'claim' or 'path into' as many empty squares as the number shows. That is, if you see a red square that shows a 3 on it, you need to click on that red square, then click on an adjacent square to 'claim' it for that red square, then click on a square adjacent to the one you just clicked to 'claim' it as well, and so on.
Your options, from worst to best: - add a tutorial (everybody hates tutorials) - add some concise text to the bottom of every page that explains the objective and how to play - find a theme that makes the objective and how to play intuitive
Other feedbacK: - You absolutely need to show which square is selected (if any). - There's either a bug or some condition for play that I don't understand, but you can't try to occupy a square more than once even if the square is empty because a previous attempt to occupy it was canceled/reverted.