Does the GOG version of Doom 3 BFG edition include the classic Doom 3 or just the butchered BFG edition? Because if not I'd highly recommend you find the classic version of Doom 3. They made it ridiculously easy by massively increasing the quantity of ammo in each pick up and allowing you to use a shoulder mounted flashlight. Some people prefer the suit mounted flashlight... but some people also have no understanding of tension and risk/reward mechanics.

Sad thing is I don't actually think the increased ammo in Doom 3 & RoE is INTENDED... but instead mass laziness. Basically the extra ammo from pickups was intended for the mini-campaign for BFG called the Lost Missions. It was intended as a balls-to-the-wall blast fest like the classics and gives you way more ammo to compensate for more enemies.