Jagged Alliance was originally published by Sir-Tech in the 1990's. Two main games Jagged Alliance and Jagged Alliance 2 were released, each with a number of expansion packs. There were also Linux and Nintendo DS ports of some of the games.
The franchise won fans of turn-based squad-level combat for its detailed modeling of various equipment, interesting characters, and role-playing conventions where mercs leveled up the skills as they were used.
Each game had a main story campaign and numerous side missions and compelling turn-based combat, but what separated JA from other games were the personalities of the mercs. The game modeled preferences and quirks of each merc and how well they worked with each other. Some refused to work with others, some would refuse the player's orders, others gained morale bonuses when working with fellow mercs they liked.
Sir Tech fell upon hard times and the franchise grew quiet in the early 2000's, although some fan mods kept some activity alive. The franchise has been picked up by Kalypso and Jagged Alliance: Back in Action released in February 2012.
See the Jagged Alliance site.