Galactic Defense Force - bug maybe?

[bjamminloe]

Vanilla install, all DLCs, achievement hunting.

Playing Fear the Dark origin. Went Fanatic Purifier. Using World Cracker to destroy everything touched by a xeno scum. I have a total of 5 planets, 291 population.

I have purified the galaxy except, destroying every possible planet I didn't inhabit. How could my people live someplace despoiled by xeno scum?!

I have eradicated everything except 1 star system, and it only has a habitat with 8 xeno scum pops. I had captured the starbase this final system, and was moving against the habitat. The Galactic Defense Force megaleet was hovering around the habitat. It had ignored me through all my planetary destruction, flying around where my fleets were but not attacking. As I moved in for the coupe de grace, I had a hard time seeing the habitat and accidentally clicked on the GDF . Suddenly that megafleet came to life and wiped out all my fleets.

Well, drats, minor set back I think. I'll just rebuild and wipe out the GDF as well. So I build up to double my naval capacity and attack.

And the same result occurs. 5 times already. I've tried every combination of weapons and ships, but nothing seems to do much good. I'll dish out 400k-500k damage to hull and kill 3 of their ships while taking 150k damage to hull and lose 200 ships?! The GDF megafleet is 0 titans, 150+ battleships, ~60 cruisers, ~60 destroyers, ~100 frigates, and around ~150 corvettes at last look. The fleet has every single weapon, so can't really rock-paper-scissors against them. The megafleet won't leave orbit of the habitat for me to send in a world cracker and end the game. When I build up a massive fleet it destroys my economy so I can't support it very long nor build a bigger fleet.

Possible Bug Description
The GDF keeps growing in number of ships (fleets of 35k just randomly show up in the system and merge with the main fleet), even though the enemy has 8 pops left and zero starbases. It also heals itself up, so by the time I rebuild to attack, it is 100%. How can this happen? Where are the ships getting built? Where is it healing?