Generation: A Novel Fabrication Game for Simulating Evolution
and Natural Selection
Katelyn M. Grasse and Edward F. Melcer
Alternative Learning Technologies and Games Lab, Computational Media Department
University of California, Santa Cruz
Santa Cruz, CA, USA
Figure 1: Overview of the game’s components. Generation is a game that requires a 3D printer (left) to iteratively fabricate
game pieces which the player uses to gradually assemble into more complex creatures (middle). The player takes a picture of
their creature design (right), which is then analyzed by the game to simulate its survival in a dynamic digital ecosystem. The
goal of the game is survival, and the player scores points for every evolutionary step they successfully take.
3D printers are becoming increasingly accessible to the average
consumer, however their potential utility within games has yet to
be fully explored. Integrating 3D printer fabrication technology
within game design presents a novel means for engaging players
and providing them with tangible representations of gameplay
elements. This in turn could be employed to increase embodied
gameplay and even embodied learning for the player. In this pa-
per, we present a novel "fabrication game" designed to teach basic
evolutionary concepts. In the game, players take turns physically
assembling components 3D printed in real-time to iteratively evolve
their creatures and observe the impact of their evolutionary choices
on a digital population simulation. We discuss the potential of this
game’s unique design in leveraging real-time fabrication of tangi-
bles to enhance a player’s understanding of principles of evolution
and natural selection.
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For all other uses, contact the owner/author(s).
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ACM ISBN 978-1-4503-7587-0/20/11.
•Applied computing →Interactive learning environments
•Human-centered computing →Interactive systems and tools.
3D printers, fabrication, tangibles, video game, educational game,
simulation, evolution, natural selection
ACM Reference Format:
Katelyn M. Grasse and Edward F. Melcer. 2020. Generation: A Novel Fabri-
cation Game for Simulating Evolution and Natural Selection. In 2020 Annual
Symposium on Computer-Human Interaction in Play (CHI-PLAY ’20 EA), No-
vember 2–4, 2020, Virtual Event, Canada. ACM, New York, NY, USA, 5 pages.
Fabrication technologies such as 3D printers are becoming increas-
ingly accessible to the general public chiey because the equipment
is becoming smaller, cheaper and easier to operate. As a result,
people have begun to explore incorporation of 3D printers into
game design, coining terms like fabrication games or playful fabri-
]. However, current fabrication games typically focus
on utilizing 3D printers to generate pieces in advance for use in ana-
log games, e.g., [
], rather than leveraging the real-time fabrication
capabilities of such tools directly into the gameplay.
Tangibles are a powerful tool for engaging users [
ing customized physical objects and interactions that deliver a
more intuitive, embodied experience [
]. Notably, within the
context of games, the embodied interactions that tangibles aord
can even be applied to enhance player experience and learning
]. However, we posit that the real-time capa-
bilities of fabrication technologies used to create tangibles (such
as 3D printers) have not been fully explored within the context of
games and learning. For instance, while there are examples of 3D
printers being used to supplement teaching methods for topics like
math, geometry or engineering, cases involving games are currently
]. In this interactivity paper, we present our initial
exploration into expanding the design space of fabrication games to
leverage the real-time fabrication capabilities of 3D printers. This is
done through the creation of our own educational fabrication game
for teaching concepts related to evolution and natural selection,
titled Generation. In the following sections, we will discuss the de-
sign rationale for Generation, as well as the potential of this game’s
unique design in leveraging real-time fabrication of tangibles to
enhance a player’s understanding of principles of evolution and
2.1 Fabrication Technologies and Games
Fabrication technology enables digital problems to be manifested in
the real world to allow for less constrained and more intuitive and
creative manipulation [
]. As a result, various fabrication tech-
nologies have been investigated to facilitate exploratory play and
problem solving, including mediums such as textiles, beading and
]. These modes of crafting have been successfully
employed to enhance playful interactivity in games or education,
but rarely both together [
]. BeadED Adventures [
] and the eBee
electronic quilting project [
] are exemplars of the mergence
of crafting, gaming and STEM education, both of which utilize the
aordances of their chosen craft materials to facilitate interest in
and understanding of the educational topics of interest [
this paper, we seek to extend the scope of hybridized (physical-
digital) fabrication games designed for learning by combining a
novel educational video game with 3D printer technology.
2.2 Embodied Educational Game Design
Integrating fabrication technology, namely 3D printers, into video
games provides a novel opportunity for creating tangibles that can
support embodied game design and learning [
]. While there are
various techniques to incorporate embodiment into games, such as
through AR or VR, the use of tangibles and tangible interactions for
embodied game design is one of the most popular approaches [
Notably, tangibles can embody (learning) concepts in two distinct
ways: 1) through the use of embodied metaphors and interactions
with the physical artifacts themselves [
], and 2) through the shape
of the artifact itself and how that represents the learning concepts
]. As a result, their benets to learning have been hypoth-
esized and studied broadly [
]. For instance, incorporating
tangibles and principles of embodiment into learning activities has
been shown to elicit boosts to engagement, spatial recall and mental
manipulation, intuition for physical interactions and mappings, and
positive feelings towards learning science content [
]. There have
been a number of embodied educational games that utilize tangibles
to teach a variety of topics such as programming [
], reading and spelling [
], anatomy [
], and animal foraging
]. Generation is similarly designed to take advantage of
the embodied aordances that tangibles provide in order to make
learning about natural evolution more engaging, intuitive and fun.
2.3 Evolution Education
Evolution is recognized as the unifying scientic theory in biology,
but teaching this topic is notably dicult [
]. Both digital and
physical games have been extensively studied as a means for mak-
ing learning about evolutionary concepts easier and more intuitive
]. Examples of digital entertainment games that feature
principles of evolution include SimLife (1992), Spore (2008), Niche
(2016) and Ecosystem (2020 expected release). Examples of explic-
itly educational games include the Evolution Board Game (2019)
and Catch a Mimic: Natural Selection (2019), the latter of which can
be played in virtual reality (VR) to encourage embodied learning.
Game designers emphasize various evolutionary principles at com-
plexity levels that are most relevant to the goals of play. However,
one major feature that these games share is that they demonstrate
how species can change over the course of many generations to
adapt to a changing environment – the core principle of evolu-
tionary theory. Generation will also help players develop a better
understanding of this principle by challenging them to design pro-
gressively more complex creatures in order to survive in a dynamic
3 DESIGN AND GAMEPLAY
Generation is a game designed to help teach principles of evolution.
A variety of core evolutionary concepts can emerge while playing
the game, including 1) natural selection, 2) random mutation, 3)
common descent, and 4) that species change gradually over the
course of many generations. Evolution is a process that involves
both rules (e.g., survival of the ttest) and randomness (e.g., genetic
mutations), therefore both elements were incorporated into the
game’s design through the turn-based construction (i.e., evolution)
of tangible creatures. Just as it is for creatures in the natural world,
the major goal of the game is to survive for as long as possible by
adapting to unexpected challenges. Players of this game will learn
to consider how every decision could aect the stability of the rest
of the ecosystem, as well as ways in which any changes will in turn
aect future survivability.
3.1 Game Design Overview
This fabrication game combines a digital simulation with physical
gameplay to aord the player a novel physically engaging expe-
rience for learning about evolution. Though we expect the game
can be designed for multiple players in a cooperative or compet-
itive format, a single-player game playing with the computer is
considered rst for simplicity. At the start of the game, the player is
provided a single printed game piece representing one member of a
homogeneous population of simple organisms. Players of the game
should be able to recognize that this starting creature is the single
common ancestor from which all future species will descend. The
game is turn-based, where player and computer alternate printing
new shapes to iteratively assemble into their increasingly complex
creature designs. A camera connected to the game analyzes an im-
age of the player creature’s physical design to measure its attributes,
wherein features like the number or arrangement of the connected
shapes are used to determine the creature’s attack, defense, speed
and stamina. These attributes are then fed into an algorithm that
simulates the creature’s population size dynamics, which aect
and are aected by the rest of the ecosystem. The other simulated
species in the ecosystem will also periodically change in an attempt
to improve their own survivability. The player alternates between
changing their creature and observing the eects of their design
choices upon the gradually changing ecosystem. The ultimate ob-
jective of the game is to survive as long as possible (see How to
Beat the Game for more details).
3.2 Creature Design
Players design creatures by connecting together a collection of up
to four types of printed game pieces. These pieces are are designed
for simplicity to minimize fabrication times (see Figure 1). Each type
of game piece is a regular polygon (meaning they are equiangular
and equilateral), and every piece has equal length sides – therefore,
for example, one hexagon takes up the same area as six triangles.
Pieces are distinguished by both their shape and color for visual
clarity, including red triangles, yellow squares, green pentagons
and blue hexagons.
The player decides when to print a new piece, but the game
restricts which shape may be printed (players choose between two
random options each turn). By restricting the gameplay rules in
this way, players are not able to plan out the creature’s design at
the start of the game, but they can determine the rate at which it
evolves and maintain some authority over its composition. Each
piece has a limited number of sides, and so is limited in the number
of pieces to which it can be attached. As soon as a new piece is
printed, the player must integrate it into the creature’s design while
following one simple rule: every piece must always have at least
two sides free. For example, triangles can only be attached to one
other shape, whereas hexagons can be attached to up to four shapes.
As stated before, the arrangement of the game pieces determine
the creature’s various attributes:
(1) Attack is equal to the number of red triangles.
is equal to the number of blue hexagons. A creature
becomes the prey of another creature if the prey’s defense is
lower than the predator’s attack.
is calculated by nding the creature’s maximum length
and dividing it by the creature’s average width along the
orthogonal axis. As a result, long and skinny creatures are
fast compared to rounder ones.
is inversely related to the amount of kinetic energy
required to move. We chose to dene a creature’s kinetic
energy by multiplying the cube of its size by the square
of its speed. Size is equivalent to the combined area of the
creature’s shapes. Faster and larger creatures expend more
energy to travel a certain distance. As a result, predators with
lower kinetic energy have higher stamina and are better able
to catch prey.
Figure 2: Examples of evolution of creature designs and pop-
ulation size simulation. (A) Players take turns printing in-
dividual game pieces to assemble into progressively more
complex creatures. The computer also chooses designs that
favor survivability. (B) Lotka-Volterra equations can be used
to simulate predator and prey population sizes over time.
Changes in either creature’s attributes cause changes in both
creature’s population dynamics. The game terminates when
only one creature population remains.
3.3 Population Simulation
A series of coupled ordinary dierential equations can be used to
model the population dynamics of each of the species in an ecosys-
tem. A classic simple example of such a system would involve two
organisms, and their population size dynamics can be described by
a pair of Lotka-Volterra equations [
]. These equations (1, 2) can
be used to model the time-dependent rates of change (d/dt) of the
sizes of populations of prey (N) and predator (P), where (r) is the
prey birth rate, (a) is the prey death rate, (b) is the predator birth
rate, and (m) is the predator death rate.
=𝑟 𝑁 −𝑎𝑁 𝑃 (1) 𝑑𝑃
=𝑏𝑁 𝑃 −𝑚𝑃 (2)
The four creature attribute variables described in the previous
section can be used to determine the prey death rate (a) – often
dened to be equivalent to the predation rate – for every predator-
prey relationship in the ecosystem. This relationship could resemble
the following example (3):
𝑃𝑎𝑡𝑡 −𝑁𝑑𝑒 𝑓
+𝑃𝑠𝑝𝑒 −𝑁𝑠 𝑝𝑒
+𝑃𝑠𝑡𝑎 −𝑁𝑠 𝑡𝑎
𝑁𝑎𝑡𝑡 −𝑃𝑑𝑒 𝑓
In this case, all four attributes from both creatures are utilized
to determine the predator’s rate of success. When the initial con-
ditions and the values of the constants (r, a, b, m) are balanced,
the equations reveal co-dependent oscillatory changes in the size
of each species’ population that are stable over time (Figure 2B).
While these equations are only an ideal approximation for modeling
population dynamics that occur in reality, they nonetheless can
provide the player with a basic understanding of the instability of
species’ rates of survival over time.
3.4 How to Beat the Game
Natural organisms do not evolve in order to reach some ultimate
form, and similarly it is not possible to "beat" this game. Instead,
players earn points for every evolutionary step they take, and the
goal is to earn as many points as possible. In other words, the main
objective of this game is to survive for as long as possible. To do so,
the player must not allow their creature’s population to fall below
a certain size. This rule should be easy for players to understand
at a glance – when the population shrinks too small, its members
will not be able to procreate as easily (or at all), leading to their
extinction. Maintaining a respectable population size is an intuitive
survival goal, but the player can also lose the game if they become
the only organism left in the ecosystem, meaning that all other
species have died o. This outcome is the equivalent of a mass
extinction event, where the stability of the entire ecosystem has
collapsed. When mass extinctions occur in nature, higher-order
organisms are the most vulnerable because they are most likely
to lose access to stable sources of food, leading to their extinction.
Using these rules, the game will encourage players to avoid making
creatures that are overly powerful with respect to their environment.
Instead, the game will challenge players to explore designs that
enable their creature to continue living in harmony with nature.
In this paper, we have presented a prototype version of Generation,
a novel fabrication game that utilizes 3D printer technology and
embodied play to teach principles of evolution. While there is prior
work exploring 1) the use of 3D printers for enhancing gameplay
and 2) crafting games for educational purposes, this game expands
the scope of fabrication games by merging the two domains. Fur-
thermore, in comparison to games which fabricate game pieces
prior to play or in-between play sessions, this game leverages the
3D printer’s real-time fabrication to aord the player access to new
pieces throughout the game. The current prototype pieces each
require 1-3 minutes to print, but cutting all print times down to less
than a minute is feasible through a redesign of current game pieces
to be more ecient for printing (i.e., smaller pieces, less inll, larger
layer heights, and so forth). We also note that the time required
to print these pieces will also naturally decrease as 3D printers
continue to improve in speed and accuracy over the coming years.
4.1 Educational Design and Goals
The rules of the game were designed to make a variety of important
evolutionary concepts accessible to any player. For example, players
will learn about common descent by witnessing multiple lineages
of creatures that evolve from the same simple organism diverge
drastically throughout the game. Furthermore, the incremental
competition between species will expose how natural selection is
only possible when minor shifts in creature design occur gradually
over time. Finally, an element of luck will demonstrate that species
evolve new traits in a random fashion and develop survival advan-
tages as a result of natural selection rather than through purposeful
4.2 Target Player Experience
This game is still under development, but we expect future players
to feel engaged and immersed when physically interacting with
their creatures, especially compared to a hypothetical case where
a computer program is used instead to execute creature design.
Requiring use of a 3D printer to generate game pieces will add
an element of idleness and reection to the game, which should
encourage players to think carefully about the advantages and
disadvantages of their design choices. Additionally, the randomness
built into this game will mean that every playthrough will be unique,
therefore those who choose to play the game multiple times will
likely learn something new each time. Furthermore, the presence
of this relatively new technology should inspire players’ general
wonder and interest in STEM, and enabling access to an unlimited
number of pieces means players can easily keep their creatures as
trophies. The physical interactivity aorded by this game will create
opportunities for embodied learning, which will likely help boost
positive feelings towards learning about evolution. Ultimately, by
designing creatures in physical space, players should develop richer
intuition and memories about their learning experience.
4.3 Future Directions
Future iterations of this game will explore incorporating game
mechanics that more realistically model evolutionary forces, in-
cluding environmental pressures (e.g., evolving in a mountainous
area penalizes speed) and more complex ecosystems (e.g., carry-
ing capacities and multiple tiers of predators). To further increase
engagement, a projector and location tracking system could be
implemented to enable players to test their creature designs in
physical space. Furthermore, in order to explore the benets of
creating tangibles in real-time on learning outcomes, we plan to
conduct studies comparing use of the current system with one that
is entirely digital.
The authors would like to thank Dane Grasse, Ethan Osborne, Max
Cronce and Vivian Pham for their valuable feedback on the game
design and manuscript. This research was supported in part by a
Faculty Research Grant awarded by the Committee on Research
from the University of California, Santa Cruz.
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