Hellgate - gamefront.com

Hellgate is an action RPG that allows you to play in a first-person or third-person perspective. Set 27 years into the future, an ancient prophecy made centuries ago has come true and the gates of hell have opened. Demons have overrun the world of man and roam our lands, destroying, pillaging and killing humans. With the world above ground abandoned, dark and burnt to hellfire, humans are forced into hiding to protect what remains of their race while making plans to take back a world that was once theirs. In the game, mankind escapes to the underground system under the sprawling metropolis of London. Prepare for a struggle for survival in a world that has become hell.