Complex sentence: Only things take a turn for the worse when Gex is visited by secret government agents who tell Gex that Rez has returned and hijacked the Media Dimension, a world which has power over all of the world's television.
Split into simpler sentences: Only things take a turn for the worse when Gex is visited by secret government agents who tell Gex that Rez has returned and hijacked the Media Dimension. A world which has power over all of the world's television.