I wanted to go for a high score, but then I saw people reaching over level 100, which I could do, but it would simply take time, I quit at L50 and as other people pointed out "Divide" is OP and basically lets player reach any level they want :D
For feedback part - I really enjoyed the game. A very good execution of simple mechanics with a great technical twist (the swarm enemy). Wish there was more upgrades but I guess you didn't plan on having 50+ levels :P
The only thing that I would actually change would be the color of player character, at some point (even in regular gameplay without Divide exploit) it is very easy to lose track of player character as it has the same color as: cursor, explosions, rams etc., and to some extent the built walls. Some hue of blue might be good as it would contrast with everything, while green is already used for rewards.
Back to back great entries, both of which in totally different style. I'm a fan for sure Stepan :)