This was a good puzzle game. I especially liked the earth section. There were a lot of variables to play with, so it felt like building rather than finding a solution.
How to beat the final battle:
Send out a wall-repairman as soon as you get damaged. Use your catapault to demolish all of the first wave save for one crossbowman. Let him make dents in your regenerating wall until the timer runs out. Victory.
Am I the first to think of this?
Thanks! No idea why this comment was downvoted. Seems we have a griefer or two about :)