Diamond Hollow 2

Game description:

Shoot, upgrade, conquer enemies, defeat bosses, acquire achievements, collect gems, all in an attempt to save yourself and your gun from the clutches of the evil Professor.

Game controls:

Control your character with Arrow Down or Arrow Keys, jump with W/Space/Up, and use the mouse to aim and shoot (or switch control schemes in the options). As you acquire more guns, use QE or 1-4 or the mouse wheel to switch between them. After collecting diamonds, open the upgrades menu with tab or escape to upgrade your guns and skills to help conquer your foes.