Excalibur: Morgana's Revenge for Mac

From ExcaliburWorld:

EMR 3.0 is a unique scenario based upon the Aleph One (Marathon) engine. It is a first-person action adventure game, featuring an epic and in-depth story line. As a Federation Marine resting after your last mission, you start aboard the exploration class Starship Kronos where you learn that your real mission has yet to begin. You are re-acquainted with the AI Merlin, who introduces you to Kronos time traveling technology, and reveals your new mission: to save mankind from the clutches of Morgana and her minions. Through untamed raptor-infested jungles, castle arenas, and war-torn streets of the future, you will wield weapons from all time periods - including the Sword of Power, Excalibur - in an effort to thwart the diabolical plot that unfolds. The EMR adventure, spread across 42 solo levels, weaves a tale of truth and honor, knighthood and bravery, and darkness and treachery. EMR also delivers 27 adrenaline pumped network levels. EMR immerses you in an amazing new world, creating an addictive, fun and unique gaming experience.