Why are there no alien races in the Icar universe?

The answer is twofold, a scientific justification and a reason.

Scientific Justification

In 1950, the physicist Enrico Fermi asked why we had not detected alien civilisations. The Milky Way is 13.2 billion years old and there are 400 billion stars in it. If there is intelligent life in a tiny percentage of planets around these stars then there will be still a huge number of civilisations. As intelligent life tends to overcome scarcity and colonises new habitats then at least some of those civilisations would have developed interstellar travel and colonised. Even at slow sub-light speeds, the galaxy could be colonised in 50 million years, which is a tiny percentage of the Milky Way's age.

Human technology is fallible and we've not been searching long. There could be remnants out there that we've not spotted. Aliens could be very good at hiding or it could be very hard to spread throughout the galaxy. There are plenty of other valid arguments against but the scientist in me has long felt it was unlikely. When I first outlined Icar, this was not the main reason.

Narrative Reason

I wanted Icar to be different. At Icar's earliest inception, I hated having an idea pointed out as being unoriginal. I wanted common themes (space travel, laser guns etc) but I didn't want humanoid aliens like Star Wars/Trek.

In early games (circa 1994) I used a horror element of "Inquistors" who were an unknown Geiger-esque alien who would take humans apart for scientific reasons. Elusive, high tech and difficult to kill, I canned the idea shortly after. If pushed into explaining them away, I would say they were an insane rogue cell of Star Sci. Then I'd blush and change the subject.

The caveat

There are no intelligent alien races around now. This is an important point because I want people to experiment with the idea of long dead races. It brings up lots of interesting questions. Is destruction the inevitable end state? Is war the only way a civilisation can die out or is civilisation governed by entropy? Long dead civilisations provide excellent exploration and technological opportunities - great for GM plot hooks. I prefer them to be used for raising philosophical questions, which is the arch benefit of playing science fiction.