LYMPHODOOM. Controls: W A S D move, mouse aims and fires, E or right click opens, 1 to 7 weapons, Tab map.

Move with the left stick. Swipe anywhere else to turn. Hold the crosshair to fire; drag it to turn while firing. Doors open as you approach.

You are a killer T cell. Shoot viruses, bacteria, tumor cells, parasites, phages, spores and the boss. Pick up glucose for health, membranes for armor, ammo and dendritic scouts for the map; MHC-I keys open gates. Three levels: lymph node, bloodstream, tumor.

Engine: Dwasm (PrBoomX / PrBoom+), GNU GPL v2. Music instruments: Freedoom (BSD). Not affiliated with id Software or ZeniMax. Source code.