I completely and utterly missed out on Natural Selection back in the day and although I have only ever played its follow-up, it is cool to see the classic map Eclipse revitalized for Natural Selection 2. Graphics sure have come a long way since Half-Life.
This is of course a free update, available now on Steam. To that end, the game is down to $6.24 (Windows/Linux) during the holiday sale. I wholeheartedly recommend it if you're willing to put in the time to learn how to play -- there's a bit of a curve (or cliff, as it were). The usual fixes and the like are also a part of this patch, which you can read about at the link below.