There are a lot of games that Tom Clancy has had a part in creating, most notably the Rainbow Six series, Splinter Cell series, and Ghost Recon series. There are also two standalone games called EndWar and H.A.W.X.. Also check out http://en.wikipedia.org/wiki/Category:Tom_Clancy for what else Wikipedia has by Tom Clancy.
All battles in these games are completely fictional!
Rainbow Six is a first-person (sometimes third, regarding cover-taking in Rainbow Six Vegas) action game in which you're the leader of a tactical anti-terrorist team, easily comparable to SWAT teams. You use modern weaponry, and some unique gadgets to stop terrorist threats around the world. It can be as tactical as you make it, because your team can do almost anything you need them to, such as securing hostages, and blowing open doors, but you have the choice of doing things yourself.
The Splinter Cell Series involves a spy named Sam Fisher, who uses high-tech equipment and stealthy acrobatics to complete objectives and/or discover information.
The Ghost Recon series is a squad-based game involving military forces and heavy tactics, to destroy enemies and prevent yourselves from being destroyed in return. Many weapons options are available, to take out vehicles, infantry, or whatever it is that regrets being in your way.
Endwar is an RTS game, not a shooter like most of Tom clancy's game, though it involves military skirmishes. This game has a very nice Voice Activation System where you can use your microphone/headset (if set up correctly) to give complete control on where to attack, what units to move, etc.
Tom clancy's H.A.W.X is a fighter-plane game that employs recently modern aircraft, land-assaulting operations, and adrenaline-rushing dogfights.