FTL and Time Dilation

I was wondering if anyone ever uses the relativistic effects of FTL travel in their games.  The closer a ship gets to the speed of light, the more it is going to experience time dilation.  <br /><br />Void travel gets around this effect by only reaching 1% of the speed of light (not fast enough for time dilation to be noticeable), and then jumping through another dimension, but what did people do before Void travel was discovered?  What about aliens who developed FTL drives before Void travel?  Do the aliens in the Rim have Void engines in their ships, or did they only acquire those after contact with the UPF?<br /><br />In my game, everyone had spaceflight before Void travel was discovered, and more time went by back on the homeworld than it did for the earliest explorers.