Is it possible to play coop?

[Androsida]

I mean to play on an empty server without any people except me and my friend

[eMYNOCK]

[sarcassm]nope.. not possible at all.. you always have to shoot at other people...[/sarcassm]


and now serious:

you can form factions with other players and you can play cooperative with them.

it all depends on your agreements between each other, if you don't want to play PVP nobody forces you... if you don't want PVE nobody forces you either.

if you don't want to see any players at all on a server... even that is up to you.

[Brigor]

You can open your lokal singleplayer worlds to your friend by setting the mode from "offline" or "private" in the settings to "friends" or "public".
Just invite him via the steam overlay by rightclick-> send invite

[M.Red]

create a new game set it to accept only friends and invite your friends then.
This leaves you with your own "Server-Style" map. you can customize this map in anyway you and your friends want

[Androsida]

Thank you guys, cleared up my doubts