We just finished a campaign of about 50 sessions and about the 20-30 first sessions were played by me as GM and my ‘‘sambo’’ and best friend as the only two players. It worked fine, maybe partly because their characters were a bit experienced and had at least one high skill each which made it not unlikely that they were sent out on certain missions as a small patrol. We made it like they had been three from the beginning and when the third died/diverged their special skills made them into a special skills team sent on certain missions (and also made it natural to add a third member when another player turned up.