Only way I found out about the game was through game reviews. I was looking for a good 4X game and thought Imperium Galactica 2 would be good, and stumbled across SEIV.
Got me interested anyway.
And never underestimate word of mouth. Specially over the internet. It becomes a marketing tool itself.
( check out
http://gamerankings.com, good review site. Well, I like it anyway!)