We (ufo2000 developers) also have plans for single player mode. At least AI opponent for playing single missions is going to be added for sure.

But as Nokia 770 is internet centered device, playing ufo2000 online may be also an interesting option for maemo community. Check ufo2000 server status page, there is almost always someone playing the game, and you may find human opponents more challenging than a stupid AI in the original X-COM games