Monolith Productions gained its initial fame (infamy?) from it's Blood game and its sequel, Blood 2. Other notable games from Monolith include No One Lives Forever, Shogo: Mobile Armor Division, F.E.A.R, and much more recently, a series of Middle-earth based games. They are also notable for their Lithtech graphics engine which was licensed for use in many other games.
Official Monolith Productions website
Monolith Productions's Mobygames page
Monolith Productions's Wikipedia page
Games developed and/or published by Monolith Productions
Blood (1997)
