This mod is only for the NodeCore game. Ports to other games welcome.
When players log out of the server, their items are left behind as non-solid floating entities, along with a floating name tag at the player's last location. Other players can punch the floating items repeatedly to knock them loose and grab them. Players logging back in will have the same items they had when logging out, minus anything removed by other players.
The intended use is for cooperative games, to prevent a player who has to leave suddenly from leaving with a bunch of supplies needed by the rest of the team. There may also be PvP applications, but these have not been explored extensively.
You cannot insert items into an offline players's inventory, including returning items you borrowed. Items need to be left somewhere the offline player will find them when next logging in, and that player will need to voluntarily pick them up.