@ steephie22
Splinter Cell: Chaos Theory has a smooth control scheme and Fisher's movements are well-designed, realistic, and coordinated. You have an array of movements and resources at your disposal to tackle any situation you face in the game, as well as different movements and resources that you can adapt to your preferring playing style. The levels are fun, creative, nuanced, well-designed, and challenging. The storyline is not unrealistic (North Korea-South Korea war, ostensibly) and very, very engaging/fun.
Medal of Honor (2010) has a somewhat brief campaign but that's a price I'm willing to pay for high-quality, realistic levels and a gut-wrenching storyline. It's by far the best FPS to take place in Afghanistan. You're actually fighting most of the game in the snow and the mountains, as opposed to a cityscape like in every other FPS ever. The weapons are very realistically modeled too. Just like in a real shootout, even on the easiest difficulty you don't survive very long outside of cover. Modern tactics such as fire superiority and shooting from cover are the only way to beat the game, even on low difficulty.