the poor performance engine is the biggest problem,when rocket said oh that's a good idea but .... it's probably because of the engine. just look at arma 2 after 5 years,this game still runs like shit. and the realistic part?i just can't feel it,zombies clipping through walls,no pull bolt animation for mosin. and the explosion looks like crap,no transition between before and after explosion. i think immersion was not what they were aiming for when they created this engine, they put all the effort on things we can't see,like the way how bullets fly and idk...