You pick Simulation, i would pick Strategy. I think Simluation, I think flight and train sims. If there was a sandbox category, yeah that would work. As it is now, there isn't. And really, i wouldn't pick either one, I would pick something in between.

And no, L4D does not "require" cooperation. There is nothing in the game that forces you do to do it. Roll it down to easy or play it solo and nope, nothing comes out the scream and says you "have" to do it. You don't "have" to think ahead in most strategy games either. You could just sit back and do whatever you wanted but you won't reach end content, just like you won't reach end content in the Sims series either if you don't try to reach it.

Sims 3 can't be put into strat OR simulation. Why? Because those catagorys contain games like Supream Commander and Arma II - Games for real MEN. They wont have no girly Sims3 put next to those games which clearly drags down thier masculinity.

Seriously though (because that was a joke) I abandonded strict definitions long ago. I mean what the hell is a fishing game?. Simulation is such a huge bracket you need to subdefine that to make sense. I use terms like FPS or strat to define 'gameplay' but not the definition of the game.

I mean Arma II has a battlezone like 'stratergy' section inside it but its a game, not VBS2 (the real military simulator with the same heritage). So is one of my favourite games a FPS? It has first person perspective shooting. A Stratergy game? It does have lots of stratergy in it, even without the command section - you can't win without a good plan. Tactical simulation? Its not SWAT 4 or CoD4 (i.e. reflex is low) but it does enable simulation of tactics quite well (see the point of the military using the simulator). It has tanks, planes, choppers and jeeps... It dosn't really simulate those things though. It simulates the interations between units on a battlefield. Aha! Its a Battlefield simulator!

Great we have a defiintion. How does that help us? Marketing. Reviews. Describing the game to someone. And of course allowing it to assume its rightful position as the BEST!!! (and only) battlefield simulator game in existence. Thus is "Battlefield simulator with stratergy, FPS and tactical elements OF THE YEAR!!!".