Got it
Today I had time to try this base-defend mission. I got a really good start, with a combat hovernet and an ortnok at the ramp... the hovernet died in the first turn, the ortnok came in and headed towards the power plant. During the second turn the ortnok died from 2 plasma grenades. from this moment it was piece of cake.
The aliens didn't spawn at the power plant and so they didn't try to enter it by blowing up the wall... this allowed me to carefully leave the main entrance and I had a long-range shootout over the next 3 hours... was frustrating and great at the same time
