Headup Games announces they are offering downloads of the full version of Bridge Constructor for PC via their Steam Greenlight page through the end of this week. They are upfront about their ulterior motives on this, as they are requesting those who take advantage of this offer upvote the game's Steam Greenlight campaign to help push it over the top. Here's word on how this game can help you build bridges:

Luckily you have several construction materials at your disposal such as wood, concrete or steel cable. Each of these materials has different attributes and will offer you countless possible solutions. But be warned, as you progress through the game it will get more and more difficult! Less budget, bigger gaps to master and even material limitations won't make this a no-brainer.