Hi, I love Xenonauts and UFO enemy unknown.
What I really enjoyed about Xenonauts apart from the game being a fun blend of turn based tactic story, research and base building, is that it feels "realistic". As in no comic book aliens, no weird future, but without plausible technology.
Having it set during somehing looking like the cold war era, made it plausible that they did not have satellite images helping them on their missions etc.
There is one thing that do break the immersion though and always make me feel it is a game design error and that is
when the soldiers mess up and fire at each other or throw a grenade so close that it lands on their friends.
Makes it feel like playing with toy soldiers instead of real soldiers.
Especially when they fire at each other from very close range, it might even be that I as a player made a mistake and clicked wrong, not sure that happens but, it removes all the feeling of realism, immersion and feels just like a computer simulation throwing dices. I think the solders should be able to fire past each other at close range, without hitting their friends, just that they might get a penalty on their aim.
But it feels very unrealistic that they would fire at a friend standing next to them especially if the soldier in front of them is sitting.
Or when they throw a grenade into a wall just where they are standing.
That is one of the few things I think really remove some from the game, and at times, when that happens it just feels ridiculous.
Imagine in real world if a soldier fire at his own friend standing in front of him or just a few meters away, in really close range, that soldier would not be popular at all.
When it happens it makes the solders feel lifeless and dumb.
These are my 2 cents on how to improve the game. In what I feel would give most bang for the buck.
Of course there are other things such as rain or snow/snow storm would make for a great mood enhancement. But those things would require way much work for what they give.