Love the game! The idea is so creative! What might make the game a bit easier would be to make the spiders a bit slower, since their current speed prompts the player (or at least me :D) to a tactic of "click everywhere and run away". But since both the movement and block placing are limited, (meaning you have to think where you place and where you can go) I would encourage the player to take more time to think about where they place the blocks to maybe bring in a bit more strategic thinking. Btw managed to get a score of 21 :D