Complex sentence: Palamo, claiming innocence, retaliated, and this began the conflict upon which the game takes place-mercenaries (the players of the game) fighting in endless battles across the developed continent almost without restraint by the governments who have hired them.
Split into simpler sentences: Palamo, claiming innocence, retaliated, and thus began the conflict around which the game is centered. Players assume the role of mercenaries fighting in endless battles across the developed continent, almost unrestrained by the governments who hired them.