I know it has been more than a decade, but this game still holds a place in my heart for having introduced me to the wonderfully tragic Warhammer 40K universe.
While the background for this game is hardly explained and the story is near forgettable (both of which presented with rather poor movies actually), the presentation gripped me from the first level.
I was no stranger to turn-based games, having played Fallout and X-Com: Apocalypse (in turn-based mode), so I wasn't expecting any stellar groundbreaking turn-based gameplay (and there wasn't any).
Yet, the semi-pious soldiers with odd-looking armor suits (on both sides no less) endeared to me right away, even though they clearly hated each other and were trading quite a lot of strong-sounding fire. The graphics of this game weren't exactly groundbreaking during that time, but it does have surprisingly good looking plasma explosions (for that time), whereas most games of that time merely rendered such explosions like bursts of watercolor.
Since the game borrowed the impressive designs of Space Marine and Traitor Marines, as well as Daemons and the vehicles of both sides, there is nothing much to say about the already understandably impressive looking sprites (for that time).
Speaking of sounds, the game's weapons were among the best sounding that I have heard during the turn of the millennium. the plasma weapons sounded way more awesome than anything that I had heard at that time and boltgun discharge was very, very beefy.
Watching my Ultramarines carve away at the Word Bearers and pass by their corpses without even looting them (which I initially found odd, but understood after having learned more about Warhammer 40K) and then going on to earn experience and become more powerful made me feel very proud of my bada$$ Space Marines. (Even so, I felt that having merely three ranks of experience above Rookie were too few, but after having learned more of the tabletop game and its rules, I understood that this is for gameplay balance.)
I couldn't be sure whether the game used the Rogue Trader edition for the rules and statistics in this game or Random Games developed its own. I found that like Fallout, having high HP or high armor won't mean a thing when your enemy scored a lucky roll and killed my Mighty Hero Terminator with a bolt pistol. That is one major gripe that I have with this game (and many others that used irritating dice rolls).
(For which I am all the more glad that Relic ditched the randomness of dice throws for more certain RTS damage-dealing conventions for its Dawn of War games.)
Chaos Gate was good, and I am glad SSI recognized that the Warhammer 40K franchise is suitable for conversion into a PC game. After SSI has gone through a few acquisitions and into the grave after Ubisoft, I was very pessimistic about having new Warhammer 40K games for the PC. Fortunately, some fellows at Relic, who may have well played WH40K games before Dawn of War, recognized the franchise's viability as an electronic venture and restarted this niche.
Here's to SSI, for having fathered the first generation of Warhammer 40K electronic games.