The creator of Tiny Tower released their long-awaited sequel today, only this time instead of populating an ever-growing skyscraper, in Pocket Planes you're in charge of an airline. Over the course of business, you have to buy new planes, expand to new cities, and transport both cargo and passengers to their destinations. Some of the more playful parts of the original have stuck around, including customized outfits for the bitizens you employ, and a look into their ridiculous lives through the fictional social network BitBook.

The core gameplay is straightforward, but if you've poured a lot of time into Tiny Tower, you'll find progression is a lot better defined in Pocket Planes. You start off with three cities and a handful of small planes in each one. Every city will have a few cargo and passenger jobs available (though sometimes you'll run out of jobs and will have to either fly to another city or pay to advertise and drum up business locally). After loading up you pick your route simply by tapping each city on the world map in the order you want it to fly in, provided you've paid the one-time fee for a spot at each airport. (One particular oddity of the map view: you use plus and minus buttons to zoom in and out, not a pinch gesture.) Once you lock in your flight path, you'll have cash deducted for fuel, and eventually get paid your fare when the plane lands. Be sure to plan ahead, since you can't change routes once you're in the air. You can upgrade airports to expand their flight and passenger capacity, though that tends to be pretty expensive.

You earn a 25% bonus to fares if you're taking more than one person to the same place. This can make it more profitable to make single stops rather than multiple ones even if the base fee per passenger is lower than alternative destinations. Hotspots, like Calgary in the above case, will give you a lot more cash for your flights, though you might have to significantly extend your network to get planes to those areas. Flights have a real-world duration, so once all of your planes are in the air, you'll be able to put your iPhone away until you get pinged with a notification. Over time, you level up and unlock new planes in the store, which is a common mechanic in just about every iOS game out there, but new since Tiny Tower.

The first thing you'll notice about your planes is that there's a lot of customization available, much like the bitizens under your command. Every plane has at least three different color categories that you can tweak to suit your preference, plus you can name each individual plane. The options extend far beyond the superficial, however. You can use the game's premium Plane Bux currency to upgrade parts like fuel capacity, engine strength, and frame weight. The aircraft available for purchase vary wildly in style, range, speed, weight, capacity, and class. Meticulous logs keep track of how much time your planes have spent in the air and how profitable they are.

Plane Bux can be acquired over the course of leveling up, delivering special cargo to hotspots that change every couple of days, or by tapping bills that fly by your planes in mid-flight. They're used to hurry up flights and unlock bitizen costumes, but they're mainly used for buying new planes. You can also buy plane parts with Bux in addition to finding them when you buy access to new airports, but then you have to pay even more Bux just to assemble the parts into a full craft. Currently, I'm level 4, and I would be lucky to get 4 Plane Bux a day by catching high-end fares. The cost of full planes start at around 14 bux, which means I would have to play diligently for three to four days to get a single plane, which in and of itself is a long time for a casual game, plus I doubt it'll get any easier as I level up.

I'm pretty disappointed that such a core part of the gameplay relies on premium currency; for me, the freemium model only works really well when you dangle accelerated progress or vanity items through microtransactions, not by making spending money a requirement to play the game. At that point, I might as well just pay for another game up-front and skip the jerking around. By all means, offer some premium planes that you can buy with Plane Bux, but you should be able to progress with coins alone.

One especially new feature in Pocket Planes is the heavy Twitter integration. Basically every second screen has a Tweet button. Now, I don't know about you guys, but I'm not prone to bragging about how totally awesome my make-believe airport is to friends and family, so seeing the tweet button as often as you do can get irritating pretty quickly.

On the other hand, Pocket Planes has an awesome social feature called Flight Crews, where you can team up with your buddies to collectively climb leaderboards for events, as well as compete among yourselves. You and your friends can win Bux prizes for hitting certain ranks internationally. Normally, getting a high score isn't much of a motivation for me, but having me simultaneously team up with and compete against my friends for a shot a high-value in-game prizes makes it really compelling to get in on the action.

The graphics, though blocky and simple, retain the chunky charm of Tiny Tower. The background in flight view changes depending on the time of day, which is a nice touch. Unfortunately, none of the graphics were optimized for the iPad, so instead of getting nice, sharp lines and a user interface that makes use of the extra screen real estate, you get something that looks just as bad as an iPhone app blown up to double size. That's actually okay, since there isn't any cloud syncing for the game either, so you wouldn't be able to pick up where you left off on either iOS device anyway. The audio is a little low-key. It has the familiar coin pick-up noise, and some fairly standard airplaney sound effects for mid-flight, take off, and notifications, but there's no music. Tiny Tower had a few catchy earworms, and I would have liked to see at least a couple of new tracks to really drive the spirit of flying home.

The good

Charming 8 bit-style graphics
Deep, detailed business simulation
Attractive small- and large-scale leaderboard competition

The bad

Aggressively pushes spending of premium currency
Poor implementation on the iPad
Obtrusive Twitter buttons

The bottom line

NimbleBit has created an exceptionally catchy brand that has spawned many competitors. Pocket Planes takes a decidedly huge leap from Tiny Tower by adding a ton of gameplay depth, but still keeps the adorable 8-bit spirit alive. The implementation of premium currency feels a lot more heavy-handed here than before, as does the Tweet buttons peppered throughout the game.

I've been a fan of business sim games ever since Theme Hospital, and since trying out Now Boarding, I've been hankering for a high-quality airplane-themed title. Pocket Planes comes close, and once they add some additional mechanics for hiring staff, I think I could spend an unhealthy amount of time playing this one. Hopefully they ease off the throttle on microtransactions, otherwise many people might start remembering why they hate freemium games.