I'll be upfront and say I don't like the 'suckless' ideology or most of their programs, but I *do* like the idea of an 'immortal' program.
It's one of the reasons I like the Fossil SCM a lot. It's written entirely in ISO C and compiles to just a singe 6 MB executable binary file. It stores all its config in an SQLite database (it's the official source control system of the project, and written by its founder also), so you can configure it easily.
I'm not keen on rationale for the restrictions in point #2. These are a product of legacy rather than a software ideal. We're thinking towards the future, not the past! With that said, it is important to keep it short, snappy, and memorable. That's just good branding. It is also very important for it to be unique, for SEO. I agree of course it should only be ANSI characters, and letters specifically (no weird characters like @ or #).
Along those lines... I propose 'Immortal Gun'. Immortal on its own isn't searchable. It's very much a WIP and more to get things moving in that direction, because it speaks to the theme of the game but also the fact it's fundamentally a technical showcase of how gracefully-degradable and basic you can make a 3D game.