Pontifex is the official sequel to a free ware game in which the player designs and tests bridges. Pontifex uses a complex physics engine called the Immortal Engine which allows the construction of many different types of bridges. Once the design is completed, the player can test the strength of the bridge by sending a train across it. Depending on the quality of the bridges' design, the train will either pass over it safely or plummet into the river below. The 3D engine lets the player view their bridge from any angle including a first-person train view. Many different levels are included, from simple to complex, and a level editor lets users make their own levels to trade with other people.
