If there will ever be a failure possible (simple suggestions I've made in the Coding forum), I have already written a possible outro text and drawn some concept art to support it (which I'm not able to scan at the moment). Here are the lines for the slides [they could also be used as paragraphs for a simple outro text]:
Slide 1:
Your results could not live up to the expectations. PhalanX was not able to cope with the alien invasion. Cutting the budget to zero the countries decide to deal with the extraterrestrials on their own account.
Slide 2:
Unity among the nations fades aways , while increasing terror attacks, abductions and other alien activities begin to undermine the moral of both population and politicians. Through terror, corruption and psionic manipulations the aliens force the nations into a reciprocal war, which swells until the main invasion troops arrive.
Slide 3:
The Antarean fleet ruthlessly encounters the remaining human forces. Using biological weapons and other knowledge gathered by continued abductions they wipe out most of the civilians and their infrastructure during the final battle.
Slide 4:
The Antarean Empire establishes a prosperous colony on the Earth; living humans are only found working as slaves, hiding in caves or fighting in other wars on other planets as genetically manipulated, obedient troopers.