If Harvest Moon and SimCity got together and had a Dragon-baby, it'd probably look something like Dragonvale.
You play the part of Dragon zookeeper. You maintain the park, construct buildings, feed dragons, monitor dragon eggs, breed the dragons, decorate the park, and keep the place clean. There is a huge variety of dragons and decorations to be had, though a fair bit of chance comes into play when breeding dragons, meaning what you get when you put a plant dragon with an earth dragon varies.
The game takes place in a 3/4 view of a flat, semi-circular, floating island that allows you sufficient space to build your first few habitats and buildings. A portal - through which visitors will come and go from your park - is already in place, but can be moved around. Dragonvale gives you a few "starter gems" to accelerate the construction of buildings and rapidly hatch dragon eggs at the outset. It is worth noting here that there are three types of currencies, each with different functions and all of which can be purchased with real money in large quantities. You will place and construct those initial buildings, and the dragons will begin to attract visitors. Each dragon draws a certain amount of gold per minute. Gold can be used to build additional structures, habitats, dragon eggs, and decorations. Different dragons earn gold at different rates, and each habitat has a "cap" on the maximum amount of gold it can hold at any time. Because all of this is done in real time there is a direct benefit to popping into the game frequently to clear out cash that has accumulated in each habitat, since it will not award additional cash beyond the cap.
Much like SimCity, Dragonvale is a sandbox game. It does not have a final goal, and you cannot "beat" the game. They joy is in acquiring new dragons and decorations, and using them to populate the landscape. There is great satisfaction to be had due to the time required to clear the landscape of obstacles and construct your world, as well as the wide variety of dragons and decorations with which you are rewarded as you gain experience, breed dragons, and acquire money.
You are given complete freedom to build meandering pathways lined with flowers and trees, and populate your exhibits with dragons that match thematically, such as earth and plant dragons. Or you can create highly efficient parks with wall-to-wall habitats. Or you can eschew taste for outlandish, contrasting decorations with volcanoes next to frozen mountains. The fun is in generating a unique park to call your own.
You can also visit parks of a friend or random players, if you so choose, and gift gems - for free - to other players. In this way it encourages players to recommend the game to friends, and to participate in the gem-giving activity since it generates additional gems. Gems are extremely valuable because they are the only way to acquire certain items and upgrade key buildings.
The artwork is also a wonderful, bright and cartoonish 2D imagining that feels somewhere between Disney and Six Flags. The dragons all have their own unique flavor, breathing fire or snow depending on their breed. You can zoom in to view park-goers, which include princesses and wandering wizards porting in and out to wander the park.
There are some misses, though. The game is unusually shallow. The game encourages player to explore the wide variety of dragon breeds and decorations in order to attract park visitors, but additional visitors have zero effect on the player. Whether every aspect of the park is piled atop one another without a road in site does not impact the amount of currency being earned. Park visitors neither benefit nor detract from the gaming experience, though they can look pretty near wandering around the landscape.
The player can place one dragon every 24 hours in a Colosseum match, with the potential reward of gems if the dragon does well - the only way to win gems exclusively inside the game. However, the outcome of the Colosseum matches are almost entirely random. A Fire Dragon might win a Cold event, or a Fire event. Higher level dragons might do better, but the results seem almost entirely random. For an event that has such a highly desirable currency this randomness, combined with a 24 hour restriction that also monopolizes the dragon (dragons in the Colosseum are not earning money since they are not on exhibit), makes the Colosseum a bit frustrating.
The music and sound effects are also repetitive and limited. A light-hearted medievel diddy plays in the background on eternal repeat, and little noises from the dragons are sparse relative to the sounds of gold clinking as you clean out the habitats (ka-ching!).
It is also almost too-easy to plunk down real-money accidentally, since the game ties into your account. Once you learn your way around the interface it's not a problem, but in the initial stages of learning your way around as a player it might seem as if almost every link points to a purchase.
That said the game is a great distraction and offers a cutesy, pleasant gaming experience for time-strapped gamers and bored travelers. You can pop-in and move a few exhibits around, collect your gold, and even build a couple decorations in the span of five minutes. Those actions can also yield tangible long-term benefits, making Dragonvale a rewarding game over the long term.