Emperor of the Fading Suns
Spin offs are not a modern contrivance, they were pretty wide spread back in the day as well. Emperor of the Fading Suns, for instance is a turn based take on an RPG called Fading Suns released previous to this game by the same producer, Holistic Design. Naturally, since the company was more RPG oriented, this game wasn't too much of an original idea, nor was it too polished. You will play on a galactic scale, which basically means a black background and here and there planet maps. The planetary maps are hex grid based, and so the feeling of this game is that it is a bit unsure of how to deliver an experience to you. While the surface elements are all there, all sort of races, all sort of planetary types, ultimately the game feels like an overblown Risk like game, that isn't really that enticing. You might want to give this a go if you're a long time fan of grid based tactics games, but don't expect an extraordinary experience. Rather a bland and not that great one, that will also require you to learn quite a bit about the interface, which isn't the nicest around. A better option similar to this one, though based in a totally different setting would be HoMM.
Great strategy game
Wow! Old as it is (I've not managed to get it to work on more recent than Windows2000/ME) it is great strategy. It is a huge magnificent hex based land/sea and network-web space wargame. Explore, build conquer, all within a well defined, complex yet clear (except in a few 'mystique' justifying places) universe. Aliends emperors, research, war-or-peace, leaders, diplomacy: whaty doesn't it have. An absolute must have for the turn based afficionados out there.