On the Blackberry Bold, there is a version of Civilization that is rather engrossing. Essentially, two cities face of and send military units at each other. The units move at a set pace depending on their type and can only be stopped by walls or another type of unit that forces them to stop and fight. It is a bit like paper/rock/scissors in that the infantry units can kill the range units (archers, cannons, so on) by walking through them essentially, unless the range unit hits them first. Mobile units, elephants, cavalry, tanks, so on, can kill both infantry and ranged units by walking over them. There is a tech that you can research that allows infantry to kill mobile units, but only if in a forrest. Ranged units can kill mobile units at a distance.
There are plenty of techs to research, on three tracks. The maximum tech is limited in the lower levels leading the player to have to survive level three in order to find out what those techs do.
The computer opponent is pretty good, devilishly good in level three, but cheats a bit. Overall, however, gameplay is rather good. I've been playing it whenever I have a little downtime and am not tired of it yet and it has been weeks since I got it.
Once again, the game is BlackBerry App World - Sid Meiers Civilization IV War of Two Cities.