Amazing! This is probably the first original FPS for Ndless. Maybe do something different than zombies, a lot of FPS'es have zombies. Of course if there's a different twist that would work too. Just the thought of a raycasting FPS from scratch on nSpire is great alone.
Well, I chose zombies because you don't really need a story, you can just start blasting them away, the level design can be simple, and the AI is easy to code due to the intelligence of zombies and the fact they have no weapons.