I've had a long-standing rule to avoid getting involved in any sort of crowdfunded activities. I didn't donate to Shadowrun or Wasteland, but I did buy and enjoy both of them (I'm plugging both of those games right now, just so you know they're good). I haven't...
Remember to make the lizards take the longest route you can when you put down your towers.
You can see the routes flying units take, so make sure they're covered.
Sometimes, it's worth upgrading old towers instead of buying new ones.