Complex sentence: The crystals combine into a new game and Bowser is meaner now because the crystals were part of a castle legend, but in a surprising move, Mario and crew invite Bowser and Bowser Jr. to play with them.
Split into simpler sentences: The crystals combine into a new game and Bowser is meaner now because the crystals were part of a castle legend. But in a surprising move, Mario and crew invite Bowser and Bowser Jr. to play with them.