Bridge Builder was developed in 2000 by Chronic Logic. It is the first in a series of physics-based simulation games.
The player must use a mostly limited amount of similar pieces of steel to construct a physically stable bridge between two anchor points. Pieces cannot be scaled or resized. When the player finishes construction, a train passes over the bridge. If the bridge holds, the level is completed. If it breaks, the player may start again. There is no penalty for failed attempts.
Bridge pieces are connected via mouse control. The SPACE key starts the train.
Bridge Builder is presented in a simple 2D interface with very few colours. Colour gradients from green to red show how much pressure is applied to certain bridge parts. There is no sound. The game offers 15 different levels, with additional fan-made levels available for download.