In Trials [games] the player controls a rider on a physics-based motorcycle from the start of the level to the end while navigating a number of obstacles. The objective is to complete the course as fast as possible and with as few crashes, known in the game as faults, as possible. The game uses 3D graphics, but is played on a 2D plane, so the rider can only move forwards and backwards. Players can also control the bike's pitch at slow speeds or while in the air.
Source: Wikipedia, "Trials HD", available under the CC-BY-SA License.