Really fun game!
It was enjoyable trying to find the best strategies. After a few goes of "normal" variety in units I eventually tried saving 100 gold without buying anything, then send in 10 of the green-guys. I can't tell if that's the expected strategy or not but you win from there.
I can't tell if they attack faster or not, but it seems like what was happening was the 10 of them would stack on top of eachother, then would kill approaching enemies before they could get a single hit in.
Amazing work here!