Welcome to The Universal World Owners' Manual.
The Universal (or A tractor.. either way..) is a customisable game engine from the early 21st century. Your world server program controls graphics settings, game logic and events, and you can adjust all this via settings, configuration files and server-side scripting to create worlds of various different types - from persistent world economies to single player adventures, team-combat games or floating art galleries. Learning all you can do with it is a long process..
If you're of a certain mentality, interested in old-school game design & development, and have a fair bit of time & patience, then you may find building a world rather fun.
More details about the game can be found at the developer's website Games for May or on Steam
Once you're on your world, F10 brings up the ingame world editor.
Check out the Quickstart Guide for a further introduction to the things you can do as a world owner.