Awesome fun and I Love the visuals!
Hard at the start, but once you have some health upgrades it becomes super easy. With maximum health the slimes only do one damage per hit so there was not really any way to die.
You can also jump onto a slime and then onto the rocks to stay safe ;)
Ammo becomes an issue later too. I never had enough ammo to kill the slimes and I couldn't die so it just became a stalemate