This here is perhaps something that could interest mappers. It's basically a puzzle game where you have to build bridges above water. You are given start hardpoints and the cost limit. Then you just place girders.
It's very fascinating and addictive, there are lots of ways you can accomplish your goals.
The game is free, you can download it at:
http://www.crypticsea.com/
When you first start playing, your bridges will always break up and fall down, it's fun to watch the physics in action.. But pretty soon you learn to make steel bridges that resemble real ones, with triangular shapes and crosses, to hold them stiff.
(There have been other more complex bridge building games by the same guys, Chronic Logic, but I think this refines the essence without extra stuff.)
I'm at level 9 in the "new" series.