The first edition of Warhammer 40,000, but different enough to call it another game. Rogue Trader was a story-based skirmish game with plots the GM (Game Master) would write up. Rules were provided for various races but algorithms were also in the rulebook to calculate the cost of your homemade units. There was a wide variety of gear, vehicles, and troop types available to each army. Players were encouraged to use other companies models with GW's own and make up rules and units.
This edition is considered the best by some players because of the massive amount of background and the free-form rules.