Just played your game. Really nice. I like it.

If you're interested in feedback:
I had a hard time colliding with my own swarmers. That might be a bug or a feature, since swarmers are not just an advantage, but also a disadvantage a times in that scenario. But personally I wouldn't let the swarmers collide with the hero or themselves.

Secondly, I found it pretty disturbing that when I wanted to click on a new upgrade, my swarmers would run into that direction. Since you implemented keyboard-inputs anyway & only have 3 skills, you might want to add upgrade-keys on the keyboard, like "Q,E,C" or something, so "Q" would upgrade strength and so on.

I love the idea. reminds me of overlord, but as a topdown dungeon-crawler. It's just fun