I think I'm too dumb to get the seasons - I just placed the towers ^^. The visuals are really nice (I like low poly graphics :-)). Also this variation of a tower defense is completely new to me. Very cool idea that you have to change the positions of your towers.
Changing the speed would be cool. Sometimes I really was looking for a fast forward option. Nice would be also if you could upgrade the range/damage of your towers.
Overall a really great game :-)