Enemies give you health, purchases add cash, instant reload for all weapons. Note: to access the terminal (shop) stand next to it (it's at the left side of the ship) and press E.
Space SWAT vs Zombies Hacked
Hold off the waves of zombies while you try and get your ship repaired and ready to fly again.
Use the shop to purchase bigger and better weapons to fight the enemy as you get further through the waves.