My game is haunted? Player in my game, but no username, cannot kick?

[Alien]

So I'm hopping around and taking fall damage as usual, and all of a sudden I see a patch of brown in my grass. I get over there, and its a player model, sitting and sipping coffee, watching the sun set over my factory (faced towards my factory, sitting on the eastern side of it). They didn't talk to me, they didn't move, and I couldn't kick them in the player management window... I posted screenshots.

[Suzaku]

Players are not removed when they quit, or you're not properly logged in. If it's the former, then it's just someone you had in your game before. If it's the latter, then that's one of "you". If you're not properly logged in, the game doesn't know what body to give you control of, so your old one is left where it was and a new one is given to you with nothing but a zapper in its inventory.

The bodies can be attacked and killed if you want them out of the way, or if you want their inventory.

[sansee]

While the game itself doesn't need access to internet, the player character is tied into your Steam ID, and if Steam looses connection (or if Steam is not running), then that will happen.