This was a confusing experience. At first I backed into the elevator and got stuck there. I had to restart the whole game to try again, and then I could just not get very far at all. Felt like I didn't have many tools to work with, even though there were many controls to try and remember :)
I'm having problems with these AAA fire particle systems when combined with other stuff that is just of a totally different level. It is hard to make a game that lives up to that quality. This is often the case with UE games for some reason.
I like the idea of TD in reverse! Keep it up, and I'd recommend Imphenzia on youtube for some programmer art++!