Here's some code:
SYNC ON : SYNC RATE 0
COLOR BACKDROP 0
DO
CLS
SYNC
LOOP
Hehe - sorry, could'nt resist making a totally pitch black game engine

.
The thing is, DBC is not really got sharp enough teeth to achieve what you want from it - really you should look into getting DBPro, which supports more funky stuff like bump maps and shaders, as well as being faster. DBC could certainly handle a 3D doom game though, like if you made a 3D version of the original doom, it could do that - it just can't cope with the visuals. DBC and DBPro both have quite limited DX lights, the lights in Doom 3 are just not possible really, you should forget that flashlight, flashlights are the bane of all FPS purists - it's like the creators are saying ''lets hide the crummy detail with some blackness''. Maybe it'd be easier to try for a Splinter Cell type goggle set - night vision for instance (night vision could be used in a horror game easily - especially if you made it restrict the vision slightly, so maybe you could'nt see things sneak up beside you). Switching between gun and flashlight in Doom3 just seemed like punishment to those who'd complain about it being too easy - one day I'll walk into ID with a flashlight and a toy gun in each hand! - lookame! lookame!, 2 perfectly functioning opposable thumbs!.
Van-B

Muhahahahaha.