Stefanie Mueller, Hasso Plattner Institute
David Eickhoff, Hasso Plattner Institute
Nils Kenneweg, Hasso Plattner Institute
Fabian Eckert, Hasso Plattner Institute
Johannes Villmow, Hasso Plattner Institute
Patrick Baudisch, Hasso Plattner Institute
While personal fabrication tools, such as laser cutters and milling machines, are intended for construction, we are exploring their use for destruction. In this paper, we apply this general concept to video games. These games take place inside the laser cutter and end with game objects being physically destroyed. Causing players to irrevocably lose a personal item during gameplay increases immersion and makes each game unique and non-repeatable.
Keywords: games; fabrication; laser cutting; destruction, loss.
We live in a computer world of plenty and it is getting more plentiful every day. As Moore’s law continues to hold for bandwidth and computer storage, we download and copy, as storing has already de facto become free. And of what we have, we make backups to make sure we will never lose it.
Figure 1: Two players are playing LaserPong by controlling panels inside the laser cutter with their rotary knobs.
With the recent advent of personal fabrication tools, this trend is now about to begin for physical matter , . According to Gershenfeld , 3D scanners and printers will soon to be found in every home. Users will regularly scan, copy, share, and back-up their physical objects, so as to have more and be save of loss.
Or will they? Voonegut explains that almost all stories involve loss at some point , leveraging the experience of loss to create emotion. In many cultures, from ZenBuddhism  to BurningMan  loss and letting go are considered as a means for personal development.
In this paper, we explore loss in the concept of physical computer games. We use tools generally intended for construction—but we repurpose them for destruction. All games involve physical destruction of objects as part of their main game mechanics.
The concept of destruction and loss has primarily been elaborated on by modern arts, often in the form of games. Several pieces give visitors the choice whether or not to destroy a piece of community property. In Helena  liquidizers serve as an aquarium for living goldfishes, which can be switched on at a player’s will. In Desu100  players can destroy a robot by pushing a button that causes the robot to hit itself with a hammer. The Recovery of Discovery  consists of a pyramid from hundreds of cases of beer; visitors can drink the beer and destroy the bottles.
Other games focus on personal loss by requiring players to risk one of their own physical objects in order to play. The video game One Single Life  destroys itself when the player’s in-game character dies, i.e., players lose the game license. Lose/lose  is a spacecraft game in which each alien is linked to a file on the player’s computer; when the player shoots the alien, the file gets deleted. PainStation  requires players to commit their own bodies, which get electro shocked and whipped when they lose.
Physically Destructive Games
To date, we have implemented three physically destructive games (partially implemented at the time of submission; to be finished by the time of the workshop). As shown in Figure 1, we have repurposed a laser cutter for our implementation. While any subtractive fabrication tool could be used in theory, e.g., milling machines, we have opted for a laser cutter, as it offers a convenient tabletop-like form factor and a clear cover that provides all players with a view onto their personal objects being destroyed.
#1 LaserPong (Figure 2) is a pong-like game in which the destructive laser plays the role of the pong ball. In old-school fashion, each player uses a rotary knob to control a paddle with the objective of reflecting the ball back towards the opponent player. If they fail to reflect the ball, the laser continues into the end zone, i.e., the area behind the player, where it destroys the personal item(s) each player had to set down before the game started.
Figure 2: In LaserPong the laser plays the role of the pong ball. When players fail to reflect the laser ball, it cuts into the personal object players have deposited, here a five-euro bill.
#2 CarSumo (Figure 3) players drive one of their own remote-controlled matchbox cars inside the laser cutter. The laser is perpetually sweeping the playfield in a pre-determined trajectory leaving a trail of destruction. The players’ objective is to push each other into the path of the laser. Pushing the other players’ cars against one of the obstacles on the playfield, increases the chance that they cannot escape the laser. The game ends, when all but one car have been burned by the laser, so as to become uncontrollable.
Figure 3: In CarSumo players use their car to push the other player’s car into the path of the destructive laser.
#3 LaserNinja (Figure 4) resembles CarSumo in that again all players drive one of their own remote-controlled matchbox cars inside the laser cutter. Every time a player picks up the star-shaped power-up, they get a chance to take a stab at the other players’ cars by controlling the laser for a brief moment. Additional power-ups allow for longer strokes or provide temporary invulnerability.
Figure 4: (a, b) Picking up the star power-up in LaserNinja allows that player to strike at the other cars using the laser.
To make the moment of destruction a key focus of interest in the game, both CarSumo and LaserNinja are intentionally designed to always give cars a chance. The laser has high power, but that power is finite; it may or may not hit a vulnerable part of the car; the car may die or may have a chance to free itself before the laser strikes again.
We implemented all three games using a Universal PLS6.150D laser cutter on top of the code base of constructable . The laser’s ability for real-time use is limited in that sending new instructions takes about ~4s. We circumvent this in the presented games in that they move along pre-computed paths most of the time. LaserPong, for example, pre-computes and uploads the complete trajectory of the ball for a game in which both players always succeed at reflecting the ball, making the game run in real-time. Only when a player misses the ball we cancel the current trajectory (the laser does this in <1s) and send the new path (<4s), which destroys the personal item behind the panel.
In this project, we explore the use of a high-powered destructive laser as a means to add real-life consequences to physical games. While the obvious consequence is that it makes game play more thrilling, we also think of it as a mechanism for helping players let go of an object by risking it in the game. We are curious in seeing what objects players will risk.
We thank Konstantin Kaefer and Bastian Kruck for their help making constructable  accessible for game development and Pedro Lopes for his help with Arduino.
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