Swen Harder (one of the persons who created GoT) mailed my this two more variants, he found in the www.

1. Silent Titan
   No dice are rolled during combat. Instead an average number of hits is used. If the average damage is not an integer then the first turn you hit hi and the next one or two turns low. for instance 8 dice skill 2 and against any skill 4 would always hit 2 first attack then 1, then 1 then repeat 2,1,1. Where as a 6 dice skill 2 against skill 4 is always 1. The name is derived from the fact that without using all the dice not a lot of sound is made while playing the game.
    
2. Total annihilation, Titan Buyback
   This is a longer format for the game for those that hate losing just because their Titan was stuck in a really poor legion. The rules are that you do not lose when your Titan dies. You must be completely taken out.. In addition you may spend 500 experience points to buy back your titan. This experience is permantly lost from your side.

Another variant mentioned in my guestbook from Arnold Patrick

• Two boards
  ...Here is a simple variant we used to play: Use two boards connected by the towers, think of the boards as 'stacked'. The towers exist on both planes simultaneously and a legion in a tower can exit into either plane. This can make for some long games, some like those, some don't... This should work with pretty much any other variant...