Very fun! Two things I noticed that didn't seem right, though:
1. The levels advance even if you don't beat the furthest one along. Example: I beat level 1, then I beat level 2, but instead of going to level 3, I replayed level 1 to get more money. When I got back to the level select screen though, level 4 had been unlocked as though I had beaten level 3. Furthermore, after level 12 was unlocked, I played level 11, and when I won, it said I beat the game.
2. The "strong" and "armored" bonuses carry over into the next level you play if you don't use them in a current level. I had already typed "armored" and "strong" in one level, but before I could summon the next unit, the one I already had on the field destroyed the inkwell. When I sent out a dot at the beginning of the next level, it had the bonuses even though I hadn't typed them for that level. I suppose this could have been on purpose, but I wanted to mention it in case it wasn't.
You should see about making later levels be longer, have more units and upgrades, and maybe even working in some sort of multiple path system. Sort of see what you can take from tower defense games.