The game play in World of Zellians is extremely similar to other city building games: you build houses, buildings, roads, demolish any problems, and so on until you meet the goals of that level. The lower levels are extremely easy, and can be completely really quickly. As you go, naturally, the goals get harder and - just like in all building games - take longer to complete.
Depending on what level you are on, you'll be building the population, building the resources, and building up your gold. Each different area also offers you a different ruler to deal with, so they will have special requests and demands that you'll have to take care of as well.
The game play in World of Zellians is really good. Once you complete an area on the map, you will open the freeplay mode for that area. You can then go back into it from the main menu and play and build any way that you would like. So, once you beat the game on the career path, you can then play any area in the game. To me, this is a great thing - as it means that the replay value is worth buying this game.
Not everyone is totally thrilled with the gameplay though. This review of World of Zellians also found the game charming, endearing, and playable, but felt that the city building mechanics lacked depth.