Really, really interesting.
I elaborated in my comment, but your entry actually solves a problem that irks me in the genre, you should be super proud.
I presume you ran short of time for content (i.e my units had aoe moves, but only ever one opponent, etc.) but I would really like to see this developed further.
It's easy to imagine cool spins on the mechanic, like high-strain high-reward moves, and enemies that build strain on you.
It was suuuuper satisfying when I figured out the strain system and started gaming it. Think I landed like a 4-5 hit combo on the Skullmurai.
Actually, it might be worth you formalizing a combo system in some way? That could potentially be awesome.
(on a side note, if you do take it further and UI isn't your jam, it would definitely be worth bringing someone on for that. You can get away with simplistic art in this genre, but these games live and die on the usability and communicability of their UI, as you probably know).
I really think there's something here worth building on.