Build your bridge with love. Be proud of your creation, and give it a pompous
name. Then eventually watch it with horror collapsing as a train runs of it,
giving you an undeniable proof that your bridge was indeed flawed. Then start
over.

These few sentences depict well a typical game of Pontifex, the successor of
the infamous freeware Bridge Builder which had already made crazy numerous
players around the world when it was released.

As its name suggests, this game is all about building bridges. Each level
confronts you with the same challenge: there is a river to cross, and it’s up
to you to devise the bridge. Three materials are available – light steel,
heavy steel and wire – each with own strength, weight and price. In order to
clear a level, your bridge must be able to withstand successfully the weight
of a train running on it. Hopefully, you can try an unlimited number of
times…

The game actually features a very advanced physics model, taking into account
compression and stretching – and of course gravity.