Cool game! I liked it how absurdly armed your spider could become (no pun intended). It would have been fun to come up against more challenges though, as at the end I was able to defeat all the enemies before they even left the corner of the screen. Just an idea, you could add more tower defense mechanics, like multiple routes (that you have to move between in order to be able to kill all of the enemies), or multiple enemy types.
A fun and pretty polished little game! Good job!