I've made an impenetrable fortress with a growing goblin army and steady stream of passive income. A dungeon masters dream.
Really fun game. Hard to get the ball rolling and get strategy right. Once you do, its fun, comical and feel powerful. The balance could use some tweaking.
More enemies would be nice. Same with allies and traps.
Adding a hotkey for placing and buying trap/goblin would good too.
Overall, great game!