There is a single-player stealth/tactics game called Hidden and Dangerous Deluxe. It was released as freeware to promote its sequel.
http://www.gamershell.com/download_3644.shtml
You take control of a special operations soldier and have to complete a variety of missions. You can alternate between each member in your squad, give commands from first person view, and map out an action plan for the units that are currently controlled by the computer. Steal weapons and ammo from the enemies you've killed to replenish your resources. There are tones of items, and an array of different vehicles at your command. Make use of distractions, bombs, and disguises as you fight your way through 9 campaigns. You have a limited number of soldiers and weapons for each campaign, so play sparingly. I really enjoyed this game, and hope you can too.