Three similarly themed movies I find interesting:
Cannibal HolocaustApocalypse Now Director's CutMen Behind the SunCannibal Holocaust' and Apocalypse Now (like Far Cry 2 btw) uses the old litterary motif from Joseph Conrad's book of 1902
'Heart of Darkness', serving as a sober comment on Western imperial and colonial mindset and mechanisms, and how easily the thin crust of civilization (illusory or otherwise) gives in to savagery. The Director's Cut of 'Apocalypse Now' adds the massacres of civilians cencorship omitted (among other scenes).
Men Behind the Sun is a Hong Kong movie showing the history of Unit 731, a covert warfare research and development unit of the Imperial Japanese Army, and the atrocities commited here, mostly chemical and biological experimentation on prisoners, and how - like in
chocolate chip cookie Germany or
Cold War US - this kind of science is morally justified as part of the war effort.
Cannibal Holocaust and Men Behind the Sun are basically horror movies.
@Thomek, if you like Trier and haven't seen it I must recommend the original (Danish) version of
'Riget/the Kingdom'.
And a nod to the already mentioned Cube, Moon, Fear and Loathing, Memento, Stalker, The Machinist, Dark City, Twin Peaks, The Road, Flesh&Blood