An original first-person shooter written for the Venu X1's touchscreen. One level of corridors, raised platforms, low beams and sliding doors, patrolled by riflemen who stay put until they see you, then chase and shoot. Their shots are slow bolts you can dodge. Cases restore health, crates restore ammunition. Every wall texture and sprite is generated by the app itself when it starts — there are no downloaded assets, no network, no account, no permissions. The game only runs while it is open and uses no battery otherwise. Controls (touch + the two buttons): • drag left or right to aim • tap the left or right edge to turn in steps • tap the upper middle (or swipe up) to walk forward, swipe down to back up • tap the gun, or press the top button, to fire • tap the status bar to open the door you are facing • hold a move zone to keep moving • bottom button quits; after death, any tap restarts It starts with a short "generating art" bar (10–20 s) while it builds its graphics; after that the level loads instantly. This is a from-scratch engine ported from a TI-84 Plus CE calculator. Source code, build instructions and the story of getting it to run at speed on a watch: https://github.com/happyc0der/doom-ports