Rather fun game all things considered. The lack of any sounds or music is kinda disheartening however. The merge mechanic is cool, but being able to merge 2 of the same tower of different levels to create a tower of the combined level could have been a cool thing to implement. The fact that the towers need to be the same level even when merging colors is also a little disheartening.
The tower defense genre feels kinda out of place for a high score based game, but having randomly generated levels after 20 makes it seems a lot better that I would have thought. Very good pixel art, and actually a pretty cool tower defense game in general!