“Skill Game” or “Skill Gaming” shall mean a game, implemented through an Inworld object: 1) whose outcome is determined by skill and is not contingent, in whole or in material part, upon chance...

If entry is truly "free" (as with a promotional sweepstakes), and the game's operator requires no "consideration" or payment from other players or entrants, then that activity will likely be permitted, assuming compliance with all other applicable laws...