I've been fiddling with the difficulty settings of Static Friction and made some interesting setups.
The Easy difficulty is relatively easy, of course, the odd battle will cause damage, but you'll most likely survive.
Medium however, is a little trickier. Enemies are tougher than usual, so you'll be using some more ammunition and take a little extra damage, but damage is pretty light so no worries there.
On Hard, however, you will need to pull some stunts, because the shit is about to hit the fan. Enemies will be more evenly balanced, so no easy targets. And don't underestimate zombies either, they are a tough foe to beat alone but in a pack you will need to be quick on your feet.
I believe i've adjusted it enough since beta testing, as many people complained it was too unfair. But i've adjusted Hard to be especially hard, to give even the most veteran players a run for their money, after all, that's what it's about.