It's an old classic. There have been plenty of spinoffs using similar names, but nothing after Jagged Alliance 2 has been any good. Except now 3 is out!I looked up Jagged Alliance, it's not a game I'd heard of, although it sounds so familiar.
Its tactical gameplay is mostly similar to X-Com, but the strategic game is very different. You're managing a small squad of characters, each with their own personality and quirks and stats. It's actually kind of role-playing-gamey in that sense. Your mission is to conquer a large map, by fighting through settlement by settlement, building up militias, and completing side missions to bolster support.
In contrast to X-Com, it is very rag-tag and dispersed however. Very much focused on individual characters and personalities, not so much an overall tech progression.