Returns the player's AccountID aka SteamID3. (
Unlike other variations of SteamID, SteamID3 does not include the "Account Type" and "Account Instance" part of the SteamID.
-multirunenvironment, this will return
no valuefor all "copies" of a player because they are not authenticated with Steam.
For bots this will return values starting with
0 for the first bot,
1 for the second bot and so on.