One pretty decent remake of UFO 1 is UFO Alien Invasion. It's open source too:
http://ufoai.sourceforge.net/
Did someone played UFO Apocalypse to death as I did ?
It took me a while to get used to operate only in one city but then I learned to appreciate the benefit of it. The city had its own life in which I loved to participate. This own life added so much to the game play. There was a bug though when I advanced far into the game that lets the game crash and I can't continue to play it anymore. Was there ever a fix to it ?