BeamNG Is an early access game, meaning its not completed yet, that being said multiplayer is still to come, as they are still updating about every month or so with new things. as far as a pc running it, most computers have more than enough CPU power to run it, and if your are over 16, or exactly 16, you can work to buy a cheap GPU like a GT 740 that can run BeamNG no problem at medium settings at 1080p.
AMD FX 8320E 3.9 ghz. gt 740 = 70 fps at medium settings.