Vaults of Vaarn is a great little OSR game by Leo Hunt. It’s a sort of a far future Dying Earth-style science fantasy setting. There’s the remains of dead civilizations littering the blue sands, bizarre technologies, and all kinds of mutants and robots roaming about underneath a dying red sun. Highly recommended.
The rules are simple, and use a variation of the Knave OSR ruleset. You roll a d20 + modifiers and try to beat a 15 for most actions. Even if you don’t use their system, it’s close enough so you can probably convert it to run in any OSR system.
Vaults of Vaarn is currently published in zine form. There are three zines currently available, but you only really need #1 to play the game.
I’ve created a fillable version of the original official sheet before, but now I’ve created my own custom version. It’s fillable and allows you to import an image. I’ve added this post to my unwieldy, ever-expanding list of character sheets.