Doom 3 is a survival sci fi horror fps not a shooter and by the time you get used to the gameplay you will love it!
Doom 3 is not a fps or a scary fps mostly it works like these move in small areas, demons will teleport in and you gonna have to use SHIFT to move fast and dodge attacks by using shift and left or right you can move in difirent directions while the imp demon is throwing fireballs at you that monster is pretty annoying it jumps at you, well thats why its called survival game so you gonna have to get used to the gameplay which is awesome later on eg move fast doge left right run towards enemy shoot with the shotgun fast!
The ai is pretty smart one of the smartest they move fast doge attacks and the zombie marines with guns are pretty tough, am not happy with how accurate they are that is because they are possed by a lost soul (enemy type)
in any case gameplay aint slick all the times eg some areas are dark, so you got to press F every now and then to use flashlight and see whats up ahead, and then switch back to weapon ( i use to do that with weapons i assign eg G grenade to quick throw them!) So we v gone to mars build labs
invented the liquidized plasma gun and BFG (probably BIG "F" GUN )
but we still dont know how to attach a flash light to our guns! in any case another thing is that the shotgun SUCKS i mean it SUCKS dont sue it much unless you stick it to someones head , eg i shoot once and i see three shots to the upper left and 4 to the lower right, duh by 2000 we supose to stabilize its fire! in any case the res of the weapons are well balnced and fun to use!
Doom 3 has a nice progression, mainly it may be FEAR as an idea but it has much better levels some cutscenes and overally doesnt feel boring, also its a VERY LONG GAME am not kidding, lets just say that crysis ha 11 levels, well doom 3 has about 27 levels DUH yeah so might wanna invest on a buy! Another cool thing about doom 3 is the enmy types propably some of the best enemy types in a fps, Now as for being hard or scary well no youll find health and ammo everywhere eg 600 capacity for the machinegun a lot of ammo so not to worry, about being scary well not really mostly you can say that it ahs some impressive graphs for 2004 and cool shadows and detail but plenty of polygons however its not scary its a pretty good game once you get the hang of it maybe not one of the best ever but a pretty good one!