The game is made tedious by a huge number of monotonous combat missions. The combat missions themselves are also tedious due to the small viewing radius, as a result of which the player has to spend a lot of time just examining the map.
All combat missions are very similar: 8-12 of your soldiers must destroy a certain number of aliens. The final battle is essentially no different from any other battle. In classic X-COM:1-2, the final battle was a large-scale battle requiring the participation of 26 soldiers, while a regular UFO assault required no more than 12 soldiers (from the middle of the game). And with some UFOs, 4-6 soldiers could easily cope. Also in X-COM:1-2 there were several combat missions that also required the maximum number of soldiers (26). There weren't many of these large-scale battles, but these battles gave the player the most intense emotions from the game.
The problem with this game is also that, according to legend, aliens are more technologically advanced, and humanity can resist them in battle only in quantity, not quality. In fact: the player's soldiers are more powerful than the alien soldiers, and the aliens can defeat the player in battle - only by quantity.
The Xenonauts game does not have the emotions that were in X-COM:1-2. When in the first battles (especially at night), the player lost more of his own soldiers than he destroyed the alien soldiers.