Welcome to the documentation Web pages for “Escape from Sagebrush Gulch,” a penny-arcade game created as the final project for ME218a, Mechatronics at Stanford University in Fall 2007. Here you’ll find descriptions, images, code and more to help you understand (and re-create, if you wish) the game and its development.
Theater of ME218a penny arcade game Escape from Sagebrush Gulch
Nora played a video arcade version of the game with a different theme called “Magical Truck Adventure” released by Sega in 2000. She remembered the game fondly and suggested using it as inspiration for the project. Benjie then found a 1913 silent film “Battle at Elderbush Gulch” and we had a game and title.
The game can be played by one or two players. The premise is that you are on a railroad handcar escaping a villain by your strength and coordination. The faster you pump, the faster the background scrolls. But you must avoid the obstacles placed in your path by the villain, which include a load of TNT ready to ignite, a section of track blown away from a previous bomb and a tied-up damsel. By jumping simultaneously over these obstacles, you continue on your way. By hitting an obstacle, you are incapacitated for a moment: momentum is lost and you have to pump to gain speed again. If you pump too slowly or hit too many obstacles, the villain catches up and the game is over. But if you survive for 40 seconds, you win a highly prized reward.
The game consists of two main components: the theater and handpump. Game play action (including sights and sounds) takes place in the theater, which is actuated by 7 motors and an RC servo; player sensory input is received primarily at the handpump, which includes 2 floor sensors and an analog input potentiometer.
The theater is comprised of two levels: the lower level houses the electronics (two proto-boards, a C32 and 3 amp power supply), penny insertion detector (opto-interruptor), cracker insertion detector (another opto-interruptor), prize dispenser (a door lock motor) and a servo for controlling the villain's motion. The upper level houses the main stage, including the two-layer background scroll (achieved by wrapping two backgrounds images around concentric dowels with different radii), scroll motor (driven by a drive belt scavenged from a computer printer), attached train tracks and obstacles and the villain himself.
Obstacles on the tracks are detected by a photo-detector placed against the inside of the scroll, which is marked with dark tape strips that correspond to the locations of obstacles on the front of the stage. When an obstacle is struck, eccentric-weighted motors placed within the pump handles vibrate to relate a tactile sense of the accident.
The puppets that represent the players pump up/down (driven by a small motor on the back of the puppet handpump) and jump up/down (detected by floor pads under the players' feet) synchronously with the players' pumping and jumping action.
The handpump is modeled after the human-powered cars used in the era of trains and seen in movies like “O Brother, Where Art Thou?” It is comprised of two floor stations connected by an inverted “V” frame, constructed with 3/4 inch sheet and 2x4 framing lumber. This frame supports the pumping handle, made of galvanized steel pipe. Each side of the handle incorporates a vibrating motor for tactile feedback, and the vertex of the handle attaches to a potentiometer which sends position and pumping velocity back to the electronics and software.
Under burlap pads on the floor stations are portions of “Dance Dance Revolution” detector pads, used to indicate when each player is jumping or standing. The control software slows forward momentum to an eventual halt if at least one player is not standing on the pads; this prevents players from remaining “jumped” the entire game and avoiding all the obstacles.
We hope you enjoy viewing the rest of this report. If you have any questions, please contact us. Best regards, and thank you for your support.
The game with its developers from left to right: Benjie, Nora and David