Once you launch for Cydonia there’s no going back, so you’d better make sure you’re ready as this mission is special for a number of reasons, most notably because it’s a two part mission. Though X-COM know the location of the alien base, the entrance to it is still not known, hidden within one of the many pyramids in that area. The squad will need to locate the entrance and use the lift there to enter the underground headquarters of the aliens, all while dealing with the aliens on the Martian surface that will do all they can to stop you.
The surface is dark and the aliens are well hidden in their structures where they’ll use their plentiful psionic attacks to try and destroy your squad. Careful actions are required to survive, dealing with aliens as soon as you spot them. Each time I’ve got to this point I’ve done so without using psionics, so having two very capable soldiers in that regard is a new experience for me and hopefully one that’ll turn the tables enough for me to be victorious. I normally lose a fair few soldiers at this point, so we’ll see how much I’ve improved since then or more importantly, how lucky I am with the map that’s generated for the surface.