My biggest complaint is that the art and the text (bar the opening screen) is so tiny! Otherwise I had fun, although those fire casters are definitely overpowered and it's particularly frustrating when they run (or spawn) off screen. I also don't feel that that this game has a strong adherence to the theme.
I think Jaco van Hemert made some great points, so I don't have much more to add, although it would appear I enjoyed the game a lot more than he did. It was very satisfying smashing all the blue guys and I got/prioritised movement upgrades in my best game so that made it quite fun.
I think the writing was very good - you did a really great job in that area. I chuckled. It also contributed some subtle world building, which was great.