X-Com.
The predecessor is Master of Magic, of course, but a re-make of X-Com with the Elemental engine would be good, in my opinion. The mechanics are there, squad based combat, squad leveling up (XCom had individual units though, not groups), building up of bases, and so on.
Why this thought popped into my mind is that the talk of remakes has been there for successful games, like Final Fantasy 7, which had a tremendous storyline, and though I tried to play it again, the polygonal graphics didnt look as good as I remembered long time ago. I never played XCom Apocalypse so dont know how its graphics were, but I wonder how many would be willing to pay for a graphically enhanced version (with new story elements of course) of X-Com. This might also give Brad a chance to write another novel for the X-Com universe.. "Alien Embers" or such.