The National Rugby League (NRL) mascots have a strange preseason tradition: they take each other on in grudge matches with their team's pride and honour at stake. The player takes control of one of sixteen NRL mascots. The gameplay is standard 3D platforming; players start in a world themed after their own team, and then move on through worlds themed after each other mascot with the goal of conquering them all. All sixteen of the mascots play essentially identically; each is a heavy character who can run, jump, and punch. Players are also able to collect digital versions of Select NRL trading cards scattered throughout the levels.

NRL Mascot Mania was released alongside the nearly-identical AFL Mascot Manor, which features very similar gameplay and an Australian Football League mascot theme.