More then that, you need a readily accessible economy, and a combat model that's fun even when you're relatively small. A deep economy, which requires lots of tedium to get involved in to any extent is a barrier, as X2 displays. And combat, I can't tell you if it's good or not, as you also need to sit through the economic tedium to take part in combat, since the starting ship is little more then a moving target, and a decent combat ship is prohibitively expensive unless you get involved in the economy.
Hard trick to pull off, indeed.
Does anyone know of a mod or tweak to make the SETI factor go above 10? I'm thinking 60 or 100 would be more appropriate to the plodding pace of the game.