While the game rules in Warhammer 40,000 Rogue Trader (WH40K-RT) are quite good there always seemed to be room for improvement in certain areas. Having the likelihood of an Area weapon shot deviating determined by the size of its effect area rather than the shooter's skill was one example that springs to mind. The Close combat rules also seemed a little too complicated. There were also possibly too many shooting modifiers, with some weapons being +2 at short range, -1 at long etc.
Recently I came across an old copy of the Warhammer 40,000 3rd Edition rules. I can see why some gamers don't like these. I think the background etc in WH40K-RT is much better. There seems to be a drive to simplify things with 3rd Ed but it may have gone a little too far - Science Fiction fans like gadgetry and detail!
Both systems have their good points and bad, so it wasn't long before I thought about trying to combine the two to create something that was easy to use but still fun and with plenty of flexibility.
This idea was to continually evolve and was eventually to become the Gemini ARAP System.