Fallen

You are kicked out of heaven, so you decide to take your revenge. You start by shooting demons to gain their souls, which are your currency to buy upgrades. Then angels are sent down to attack. When you beat those, you get shot out of a volcano to heaven to fight against the boss. 

Made for Hack Club Game Jam (Campfire, then Ember).
Theme: "Beneath the Surface"; Our take on the theme - hell.