I used to play on DominateGame but left because they erase your game history after awhile. One thing I liked there was that you could only fortify something like 7 troops max from one country to another at the end of your turn.
Maybe this could be turned into a 4th option for fortifications (adjacent with 7 max). I think it makes the game a lot more strategic. For instance if you play super defensively and do something like build on Peru the whole game, an opponent can take all other continents and surround SA. The player on Peru will then lose even if he has 10x the troops because he can't move all his armies to the front line fast enough.