Nice work! It took me a second to realize that it actually was an RTS, and when I did, I kind of just spammed healers and two-handed swordsmen until I won - I only upgraded them once near the end. If troops had a certain cost to deploy (like sun in PvZ for example) it would have made the game feel more tactical and rewarding. Perhaps if the arena was wider, and you could reposition the printers to areas of the map in need it would make the game more about strategising than spamming. Good game, just it's a bit too simple for something of this genre right now.