Complex sentence: The opening sequence, in which Riddick is escorted into Butcher Bay, is a tribute to "Half-Life", and the game's hand-to-hand combat was inspired by "Punch-Out!!".
Split into simpler sentences: The opening sequence, in which Riddick is escorted into Butcher Bay, is a tribute to "Half-Life". The game's hand-to-hand combat was inspired by "Punch-Out!!".