We don't have a backed player guide for Factorio yet. How many can play depends on mods, world and play style. The price follows memory, not player count.
Set up your server for Factorio
The console runs in your browser, and you edit files there or over SFTP. Values such as player count or world name are fields, depending on the game.
Multiplayer → Connect to address, then address and port. Factorio uses 34197 (UDP) unless told otherwise.
What if my mods don't match?
Game version and mods have to be identical for everyone. If something's missing, Factorio offers to fetch the server's mods from the official mod portal when you join.
Does Space Age run on the server?
It does, but then everyone who plays needs the expansion as well.