As far as net play, I love Return to Wolf. I personally like the historical feel to the game, and the settings, but also having 4 different player classes (medic, engineer, soldier, lieutenant) creates great team dynamics. For instance, if you play a medic, you can give other players health packs to regenerate hit points, and even revive them when they've been killed (provided they weren't blown to bits, or burnt to a crisp). If you're an engineer, you can plant explosives which destroy map objectives, or barriers to key access points. If you're a Lieut, you can pass out ammo packs or call in air strikes. And soldiers can carry some pretty heavy firepower.
To win, you generally need players in each class on your team, actively supporting each other....