It’s the gameplay mechanics that they become used to. The way that players instantly accelerate when they move, they don’t build up speed. “The weapons really don’t have a lot of power” [in RO2]. They’re all very weak. The way they handle… They’re like: “I hate Red Orchestra, I can’t play it.” Well, why? “Because the guy doesn’t move like he does in Call of Duty. Call of Duty has greatmovement.” Why is it great? “Because it just is, I just like the way it works.” So you don’t like the momentum system in Red Orchestra? “Yeah, it sucks, it’s clunky, it’s terrible.” Well, why? “It’s just because I’m used to this.”
I make it sound like there was a combative conversation, probably because I get a little emotional when I think about it. But it was really a calm discussion of, “What don’t you like?” and “It doesn’t feel like Call of Duty.” Almost every element boiled down to “it doesn’t feel like Call of Duty.” And really, watching some of these guys play… one of the things that Call of Duty does, and it’s smart business, to a degree, is they compress the skill gap. And the way you compress the skill gap as a designer is you add a whole bunch of randomness. A whole bunch of weaponry that doesn’t require any skill to get kills. Random spawns, massive cone fire on your weapons. Lots of devices that can get kills with zero skill at all, and you know, it’s kind of smart to compress your skill gap to a degree. You don’t want the elite players to destroy the new players so bad that new players can never get into the game and enjoy it. I’m looking at you, Dota. [laughs] Sorry.
But the skill gap is so compressed, that it’s like a slot machine. You might as well just sit down at a slot machine and have a thing that pops up an says “I got a kill!” They’ve taken individual skill out of the equation so much. So you see these guys—I see it all the time, they come in to play Red Orchestra, and they’re like “This game’s just too hardcore. I’m awesome at Call of Duty, so there’s something wrong with your game. Because I’m not successful at playing this game, so it must suck. I’m not the problem, it’s your game."
Quite a good article on Call of Duty being an easy FPS to get the hang of;
http://www.pcgamer.com/2013/03/13/call-of-duty-red-orchestra-2-interview/