You might have encountered games about bridge building before. These games don't tend to vary very much from each other, and this one doesn't either. X Construction Lite is a Pontifex clone.
The idea is simple. Using a limited number of segments, you must build a structure that's capable of sustaining a traversing train.
The challenge in X Construction is that you only get enough segments to make it barely. Being a train bridge, you must first sacrifice some pieces to act as the train tracks. That might be annoying, but at least you know not to fiddle with building arched bridges.
You get 27 levels with progressive difficulty, as well as a Free Build mode if you purchase the full version.
Unlike in other Pontifex clones, in X Construction structure points are fixed on an orthogonal grid. This limitation means that beams will vary in maximum length depending on their angle, which considerably reduces the degree of freedom.
I never liked Pontifex nor any Pontifex clone that I played. Although the idea of building bridges and experimenting with structural stress sounds fine in my books, I always tend to put aesthetics before efficiency and hence, I never have enough bridge pieces to finish my work. When I do concede and try to work out with what I have, the results are almost always uneven, ugly, and critically flawed. In case of X Construction, things are even worse due to the design limitation of the square grid.