Hi,
I think the following feature is missing: For each player, show the average time each one of his moves took him to complete.
Knowing this number, you could create a new game and invite only 'fast' players, for example, only players with Avg. move time of 10 hours or less can join my game.
This way, 'fast players' will be able to play with other 'fast players'. Important - nothing changes in the game. Each move still takes 24 hours. Player that will play 'slow' will simply ruin his statistics, and later will not be able to participate in 'fast' games.