Pellet Tower. Dart Tower. Squirt Tower. Swarm Tower. Not only did you rip the names from DTD, but you also copied their descriptions word for word... poor form.
after a while build options are gone...
I'd suggest either upgrading the tech tree, or allowing building on "space platforms" ie add more squares for a cost.
What a great start! I really like this game. One problem I'm having is keeping track of my animals exp and leveling... better tracking of that would be nice, rather than having to go into camp to check out their status. Maybe even selecting where extra points go to when they level??
5/5 anyways... the Owl is money as hell.
What this game needs: siege or some other type of AOE with little to no armor and slow recharge. That would allow a player to wipe out the spammed lane.
Another suggestion would be to change the Charge prereq. With 20 kills it's a rich-get-richer positive feedback cycle. Get more kills, get more guys. Get more guys, get more kills... etc. Maybe have a charging meter and the less you send the more your charge builds?
Also, as a minor graphic upgrade I'd maybe like some lines to denote the lanes... I hate sending a guy to the wrong place on accident.
There's a ton of potential with far more advanced upgrades (defending, castles, etc) that I'd love to see. In the meantime 5/5.