The forces of Heaven and Hell have been locked in eternal combat, and in the world of Eidos and Playlogic's Infernal, both sides evolved alongside humanity and set up intelligence agencies. Etherlight works as Heaven's CIA while the Abyss runs jobs for Hell. However, top Abyss agents have been turning up missing, forcing Hell to snatch up an ex-Etherlight agent named Ryan Lennox by imbuing him with Infernal powers. In joining, Lennox learns more about the Abyss and his former employers than he intended.

Infernal's superb graphics will grab more attention than any other aspect of the game, thanks to detailed characters, environments and lighting effects. Players with PhysX cards installed will enjoy larger explosions with a higher debris count. With that being said, the game is a straightforward shooter with a number of different puzzles to overcome. As a newly employed agent of the Abyss, Lennox gains access to a number of Infernal abilities, most prominently used to add an extra bit of kick to any weapon he carries. Other tricks include temporary teleportation, the ability to see hidden objects and a minor amount of stealth when rolling. Lennox can also rip the souls from downed enemies, replenishing his health while simultaneously searching their bodies for ammunition and keycards. With the exception of the soul drain, special powers rarely come into play except when battling bosses or solving puzzles. The large majority of the game relies on old-fashioned firepower as the player guns down waves of oncoming troops while following a linear storyline.

The game has a number of interesting features, including the ability to lean against cover and jumping out to shoot targets. Players can also do "cover fire," where they point the gun around the corner, minimizing exposure, but sacrificing accuracy. Players will also want to keep an eye out for well-placed explosive barrels to help make the most out of their ammunition. The game lends itself to a couple of questions; like do plate glass or wooden crates really offer sufficient cover against automatic weapon fire? It doesn't matter, given the context of the game, and the fact that the artificial intelligence often tends to be mixed. Enemy soldiers will roll out of harm's way and duck behind cover, but they also have the tendency to shoot at walls in an effort to get to the player.