City-building game Airborne Kingdom was a really new, interesting twist on the genre, challenging you to balance the growth of your flying city with its physical needs: Keep it balanced so it doesn't tip over, keep it agile enough to move forward, and keep it supplied with supplies from the surface. It also had a world to explore, with a real story, ending on a cliffhanger reveal that gave your flying city a new mission. It was a critically-acclaimed city builder in the sky... Read more.