I was pondering the kind of games missing on the Pocket PC, because I realize that although there are some very cool games out right now, few of them are truly engaging for more than a few minutes. Sitting for hours, engaged in a game that kept my attention firmly in place. There have been some great games created since then, but none that truly captivate me for long. The Gathering, it's a card-based strategy game that's very addictive and fun to play with friends. This PC game has been extended to perhaps five different versions of the same game, and it continues to sell.
People enjoy it, and the replay value is there.
A game like this on the Pocket PC, with simplified rules and controls due to the unique input methods a Pocket PC has, would be extremely popular. The basic concepts behind these games would work well for any genre. If you need a strategy game for your PPC while waiting for someone to get around to porting freeciv or cloning Civilization you should definitely check it out. I loved it as a pen and paper RPG, and on my old Apple IIe it was a blast to play as well. MST Please, Civilization, Master of Orion, or at least a clone.