Overall it's a very basic TD, essentialy the same towers versing the same mobs. However since i like TD's, i played it out for 2 maps to fully see what it was like but was quite boring. I feel as though the later waves are nice and hard but there is no progression towards it and that it should be a bit more linear. Also you can win even though you don't kill the last boss =/.
There are a few things i feel that would help improve the game play.
-Seeing different types towers would be great, eg. aoe towers, chain towers, slow towers or even buffing towers. Also feel as the water tower is pointless as it can only be placed in one spot even though the lake is 3x3 (maybe bigger). Oh also maybe make the oil miners a tower that you can place so people understand what they are.
- Enemies: they all have the same feel apart from when there are less which only indicates that they take a few more hits. That being said having health bars would be great aswell. Also maybe have a fee other mini bosses to shake things up or even maybe an event on how long you can last say after the final boss to see how good your tower placements are.
-Level: Maybe change up the background style to give it a new look or different themes.
-Ui: After a little while i managed to figure out what the rest of the icons to the top right meant, maybe make them abit clearer.
Anyways those are my thoughts that i feel would help the game out. Hope it was good feed back =]