Fans of challenging physics-based puzzlers won't have a complete collection without X Construction for Android. This bridge-building game quickly becomes more difficult, requiring some forethought and a lot of concentration.
In the game of X Construction, you're a contractor who's been hired to build bridges using a limited number of materials. Strategically place steel beams, or girders, on the screen, doing your best to create a structure that's strong enough to allow a large passenger train to cross over it. The app's quick tutorial recommends triangular structures, but it quickly becomes obvious there's a whole lot more to it than that. The only way you'll learn more about what works and what doesn't is through trial and error.
To create a bridge, you just drag your finger across the screen, being as varied with your support-beam lengths as you like, connecting the end points as you go.
Each level presents different challenges that you'll need to overcome by designing and building the proper bridge for that specific challenge. The environments will change, the valleys will become deeper, or the span of the gaps will widen. Usually, this means you'll be given more girders to create a roadway with, but the concept is always the same.
As you might guess, the levels become more difficult as you progress, but X Construction doesn't pace itself very well. The first few stages are very easy, but by level three, they're extremely difficult.
The controls are simple and responsive. You can add a girder, delete a girder and undo whatever change you just made. I found myself clicking the "Undo" button a lot. The actual bridge is made up of tiny dots and lines, which are easily blocked by your hand. You can't always see what you're doing or where you're supposed to be putting your finger. This is the game's biggest flaw.
When you feel confident in your bridge's ability (or you're just stumped, and want to see what happens with the design you have), hit the green "Play" button on the left side of the screen. A huge train will roll in, and put all kinds of strain on your little bridge. If the stress is too much to handle, individual girders will begin to snap, and the train will fall to the bottom of the valley. When the train falls, a morbidly hilarious, yet also kind of cheesy, sound byte of passengers screaming will play.
This app isn't especially complex, and some of the game's physics don't quite resemble reality. Unless you really like puzzle games, you might want to try the free version of this app before committing to the full version.