Good concept, but very hard to understand (and thus, enjoy, unfortunately).
The graphics are pretty good! It's easy to understand what's on the the screen.
But on the other end, it's very difficult to understand what to do, and since it took a lot of retries to have an ennemy with the stone base to spawn, I missed out on the turret for nearly all my games, never knowing what to do with my evergrowing pile of bows... ^^'
(also, it might just be me being stupid, but I didn't understand you had to use the arrows to move around, I figured it might be a point and click game where you have to defend the goblin, and wondered why my mouse wasn't picking up items for 2 solid minutes)
Although, once I finally got it, it became a bit more fun! I liked the fact that you added two different levels, it shakes things up a bit and allows for different strategies.
Overall, interesting take on the dungeon defense genre, it just needs a bit more explanations.
Good job! =)