It’s a game version of what you imagined the little Lego vehicles you pretended to create as a kid did in your imagination. It’s pretty fun, kinda grindy in campaign mode, but at least worth an afternoon if you like any other vehicle building pseudo engineering game.
And yes there is multiplayer, including multi-single player where other people’s vehicles invade your world. It’s balanced enough that you shouldn’t usually get curb stomped by them.
If it’s a shirt, there’s not really labor involved outside transportation.