When I go to play a game, I get heavily invested in it. For me, immersion and focus is everything. I am that person who spends 20 hours prior to even touching an RPG like Skyrim figuring out the best mix of mods to add to it! And unfortunately, with Alien Nations, this playstyle of mine was a hindrance to any enjoyment. Alien Nations is a game where combat/story is heavily tempered by a need to build, gather resources, build many beautiful cities, and make your citizens happy. Unfortunately, it is NOT a game like others in its genre, as it is particularly hard to get immersed in it, largely for two reasons: the lack of graphical variety; and repetition between missions. Graphically, you can hardly tell you are on different maps, as the trees, animals, and every other detail look identical, meaning that missions largely feel the same. This leads to the second, bigger problem: repetition between missions. Most missions require the same idea: tech up, build up, and hit some minor, time-consuming goal. While this is not a problem persay, the sameness between maps made this into a chore, and it often felt like there was no real difference between the titular "nations," as they had identical tech trees with only cosmetic differences between units and buildings. You end up doing the same pointless tasks, mission after mission after mission, and these issues make it ill-suited for immersive playing. However, it works surprisingly well as an AFK game where you are engaged in another task while it runs in the background, with a minimum of your time investment, and in this regard, it can be very enjoyable. If this sounds fun, get it by all means, but do not expect either immersion, vivid imagination, or striking gameplay, for beyond the quirky intro and the alien look, there is nothing interesting happening. Try Cultures or Settlers instead, or better, try "The Nations," this game's sequel, where many of these problems have been solved.
