Excalibur: Morgana's Revenge is described as 'first-person action shooter game that combines time travel to take the player through the Jurassic period, Camelot period, and into the future chasing down Morgana' and is a First-Person Shooter in the Games category. There are more than 10 games similar to Excalibur: Morgana's Revenge for a variety of platforms, including Windows, Mac, Linux, Steam and Xbox. The best alternative is Half-Life. It's not free, so if you're looking for a free alternative, you could try Hexen II. Other Excalibur: Morgana's Revenge like games are Doom (Paid), Quake (Paid), Black Mesa (Paid) and Clive Barker's Undying (Paid).
From the independent studio that brought you Contrast, We Happy Few is an action/adventure game set in a drug-fuelled, retrofuturistic city in an alternative 1960s England. Hide, fight and conform your way out of this delusional, Joy-obsessed world.