It's the time. I was part of a group of pretty serious board game players. We played Axis & Allies until we didn't need to think about the first 2 or 3 turns. For serious games, we'd play Civilization (not the Sid Meier version), Titan, Kingmaker, occasionally Third Reich. Even with that, we only played 3 or 4 games of Dip. It was totally the most fun game, but it was also very difficult to work out the scheduling. As written, with 15-minute turns, 5-minute builds, and the time to work out the moves, you're talking 45 minutes per year. A typical game here lasts until 1912, so that's 9 hours--and if the game gets good, it could be a lot longer.