you haven't destroyed the Tasoth Factory yet.
Thanks for the tip. Indeed, after a bit, the Tasoth Factory mission spawned, and some new research became available. Let's see where does it leads to.
EDIT:
Finally!
Serious spoilers and mini-review follow:
Spoiler:
After some in-game time, the Atlantis mission spawned. Essentially the last level of TFTD where Cthulhu is. I forgot what it was to fight Tentaculats! Fortunately I brought every yellow suit soldier and a wall of sonic weapons kept them at bay. The tasoths are a tough race. They go down faster with darts than sonic weapons. Is there a way to manufacture the ammo for these? Maybe I took off before finding it out.
The result of this battle, as the hint said, was the analysis of the Stone of Atlantis, then Cydonia or Burst. When this research was on-going, I assembled my team with every soldier with a P rating of 90 or more, so to be essentially immune to psi attacks. As soon as the research was completed the Avenger, which was waiting for months, took off.
The surface battle of Mars (pyramid level) was sort of easy, except for the insane number of very dangerous cyberdisks. No casualties but several wounded yet able to continue. The next level is where the fun really started:
The next level was the regular brain level. This is when I got lucky. My main team spawned next to the brain level. I know, because one of my tricks (is it a cheat?) is to move the cursor around looking for the missing pixels of the hidden shapes. At the other side of the wall, there was this empty giant room, and then a spherical thing was pulsating. Next turns, it was to carve a small path using pick axes and then a Blaster bomb. The End.
My comment is the end game screen repeated twice. Like when the Brain tried to negotiate and it's blasted away, the whole sequence of screens repeated a second time. If I remember correctly it was the same content as vanilla. I re-loaded and cancelled the mission to see what the Losing screen looks like. The same as Vanilla, and also repeated twice. I don't know if this screens repetition is a sign of a bug in the .exe or in the mod.
Thank you Solarius for the XCF mod. It was fun to play.