Interesting idea, I liked it. My only gripe with it isn't the performance issue (even though I encountered) but that units (enemies and mine) go off screen, have battles, spawn souls and there is no way for me to get them. Even when I zoom out to max level.
Overall, pretty good game. I liked the pattern matching part -- makes building towers and/or attacks more interesting. Although right now (and I am guessing this is due to jam constraints) there is a clear "winning" strategy that dominates anything else available.