I can think of two ways to reduce the number of factions in a game. Each has certain disadvantages, however:
1. Start a new game. Open the Scenario Editor (Ctrl-K). Use the Eliminate Faction option on the Scenario menu to eliminate the factions of your choice. The (possible) disadvantages are that you won't receive a score for the game and you might see part of the map.
2. Create a scenario. When doing so, you can add as few factions as you like. The (possible) disadvantages are that you will see the map and know the starting locations of all the other factions. Also, the scenario editor is tricky if you haven't used it before.
Petek