Have you ever played Sim City and taken a perverse enjoyment from surrounding your residential zones in power plants, landfills and industrial zones while they wither away to abandoned slums? Or is that just me? Either way, there's something for each of us in Megacity HD [$1.99]. Despite its looks and inspiration, this is a puzzle game, not a building sim. And it's a little rough around the edges. But it's smart, and it has the heart of a city builder � with none of the Farmvill-ian frills we're all too used to these days.

You're presented with a 6�7 grid of empty grass, and a queue showing the current tile you can place and four upcoming tiles. These tiles represent buildings and civic projects: houses, power plants, hospitals and the like. Everything but the residential tiles modify the spaces around themselves in unique ways. Think of it as property values � while the properties on the outgoing side of a water treatment center may not mind it, the properties in the path of the intake probably aren't going to be worth as much as they otherwise would be. Megacity HD applies that kind of logic to parks (great for the whole neighborhood), landfills (no one wants to live near one) and many other locales. As you raise or lower a space's value, the tile on it gets a visual upgrade or downgrade to match. Slums ahoy!

To succeed you need to reach a certain value of housing in each column when it's positioned on the far left side. You'll start off with a softball goal of four points per column. If you can increase the value of four houses out of six spaces by just one point each, you'll meet your goal and increase your overall score. Then the whole board slides to the left, and it's the next column on the right that's being scored.

Because every column gets scored eventually and your goal keeps rising, you can't just shove all the negative modifiers off to the far right and forget about them � they'll come back to bite you in the end. But using the right edge can be a valid strategy for some things because fresh tiles don't pick up modifiers from old buildings. You can't choose which tiles you'll place, just where you'll place them, so balancing the positives, the negatives and enough residential in each column is quite the challenge. The genius of Megacity HD lies in the way it will keep you thinking six full turns ahead at all times.

This genius is slightly diminished by the luck-of-the-draw aspects. There are times I've found myself begging the game for a single residential tile to pop up, and my best score by far was in a play-through that rarely pulled out the big negatives. For competition on truly even ground, it would be great to see an update that brings in challenge modes with set tile sequences. Custom music support would also be nice � the orchestral track is impressive, but won't always fit everyone's tastes and moods.

But first things first: Game Center leaderboards are missing, and they're badly needed. There's a local scoreboard and a custom online leaderboard, but neither is implemented very well. The developer has mentioned in our discussion thread that he hopes to bring in Game Center support soon, thankfully. Hopefully the in-game achievement system will also make it over to the service, but I find myself missing those less. Megacity HD includes a leveling system with seven unlockable tiles to earn, each with its own special property. Earning them has been more than enough of a meta-game reward for my needs.

If you're up for a bit of a challenge, you'll find one waiting for you in Megacity HD. You don't need to be brilliant to enjoy it � the score of each square is displayed on screen, so if you can handle a bit of basic addition you'll be fine. All you really need to do is pay attention. In return, you'll find a satisfying puzzle experience that leaves you tantalized for one more shot at building the perfect city.

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