It's like the game is made with the sole intention of breaking it (in a good way).
Somehow on my first run I won with just 23 or so dudes: I remember having 1 max health and a whole bunch of decay at one point, so I was dying immediately over and over, until I got a card that reverses decay and armor, and defeated the boss. Since then I tried, like, 4 times to replicate that run, with no luck at the moment :)
Amazingly addictive game!