[Ward]

What about ganging angainst the cheater? The game objective will be temprarily changed to: "Evil parasite has taken control over two empires. It's imerative to destroy this threat before it spreads further?" All players make alliances. With this approach you take the wind from cheater's sails and the game still remains fun. After som time the cheater will find himself in position where he always loses even if he controlls 2 empires...