From the itch.io page:
It's the Sixth Edition, or so.
This is a fantasy roleplaying game. It's Powered by the Apocalypse, but don't worry if you don't know what that means. It's simple! And it's got lots of places for you and your friends to make it your own.
There's five different character sheets, one for each of: Cleric, Fighter, Thief, Wizard, and Dungeon Master. There's no separate rules text, it's all on the sheets!