Shadowgrounds was originally going to have 14 missions instead of the final 11. However, we soon dropped 2 missions because they would've been boring and not necessary for the plot. The last mission that was cut was an Alien Pod defence mission, which would have shed more light into the story and the Alien Mothership's role in it. And it would've featured a lot of aliens. A lot.

Frozenbyte artists screamed in agony when the design team came up with an illustrated plan for the mission, but eventually we realized that we would not have enough time to make the mission, and it had to be cut.

Maybe it will make some kind of a return in the new game, though...