CS377: Designing Serious Games

P1: Those Who Play, Teach

Fall 2025

Fish Reproduction

Zoe Clute, Arnav Mehta, Khushi Malde, Jason Lin

Note: The final output can also be viewed on Google docs at https://docs.google.com/document/d/1iNmIgWhAd0ZES2JXpn_1BbgqiRQMhw7pquhr4ACLVbk/edit?usp=sharing

Overview

In our game Fish Reproduction, we aim for young adult players to take on the roles of fish species living in an Indonesian coral reef, with the goal of growing their populations by gathering resources and reproducing. Each species has unique needs and reproduction mechanics, and players need to strategically manage food, water, coral, and warmth to survive. Tokens and illustrations help introduce  sensory fun, while challenge, fellowship, and discovery emerge through the game’s dynamics of competition and random event cards. Throughout the game, players must adapt to environmental changes and challenges (represented by event cards) that impact the reef’s health and resource availability. The competition for limited supplies reflects real-life ecological dynamics. The game ends when the reef’s resources are depleted, with the player having the largest fish population declared the winner. Ideally, the learning outcomes of this game are informational and implicit: players gain understanding around coral reef ecosystems and Indonesian reefs in particular while interacting with a market mechanic that teaches ecosystem balancing, resource management, and long-term planning. Additionally, everything in the game (and in real ecosystems) comes back to energy, or can be converted to energy. This is intended to teach players about the cycle of birth, life, and death that occurs in all ecosystems without any energy really being lost. While we still have many changes and improvements that could be made, we’ve come a long way since our first version of the game, and have learned a lot along the way!

Rules

Fish Reproduction Game Rules

Overview

Welcome to Fish Reproduction! In this game, you represent a species of fish living in an Indonesian coral reef. Your objective is to grow your fish population as large as possible by gathering resources, reproducing, and navigating the challenges that reef life presents.

Setup

Each player starts with:

1. A species card that explains how your fish reproduces and provides important details about your species.
2. 5 energy tokens.
3. Fish tokens:
   • Banggai Cardinalfish, Striped Poison-Fang Blenny, and Humphead Parrotfish start with 2 fish tokens each.
   • Blacktip Reef Shark starts with 1 fish token.

Reef Bank and Ocean Resources

• There are 4 types of resources in the reef bank: Water, Coral, Food, and Warmth.
• Each resource type is divided into 4 columns, with 8 resources in each column (2 resources per slot).
  • Column 1: Costs 1 energy to pick a resource.
  • Column 2: Costs 2 energy.
  • Column 3: Costs 3 energy.
  • Column 4: Costs 4 energy.
• If the reef bank runs out of a resource, you may venture into the Ocean which has unlimited resources, but it costs 6 energy per resource.

Game Play

Each turn, a player can:

• Perform any or all of actions 1, 2, and 3 in any order, or
• Perform action 4 instead.

Actions (1–3):

1. Get one resource (and only one):
   • You may pick one and only one resource per turn from either the reef bank or the ocean.
   • Resources from the reef bank cost 1–4 energy depending on the column. Resources from the ocean always cost 6 energy.
   • Always take from the least expensive column first (e.g., if Column 1 has resources, you must take from there).
2. Reproduce:
   • If you have the right combination of resources, discard them and follow your species card to reproduce.
   • You can reproduce multiple times in a turn as long as you have the resources.
3. Exchange a fish token for energy:
   • Sacrifice an existing fish token to gain energy.
   • Depending on your species, this action gives you 4 or 8 energy.
   • You can exchange multiple fish tokens per turn.

Action 4:

1. Gain energy and trigger a random event:
   • Instead of buying resources or reproducing, you can gain 3 energy for free.
   • When you choose this action, immediately draw and play a random event card. Event cards change the game by impacting resources, players, or the reef itself.

Reef Events (When a column is emptied)

When a column in the reef bank runs out of resources (i.e., the last resource in that column has been taken), the player who takes the last resource must pause their turn and follow these steps:

1. Draw two event cards.
2. Choose one event card to play and return the unused one to the deck.

• The chosen event card will take effect, impacting the resources, players, or the reef itself.
  • Example 1: If the event card says, “Add 1 coral,” you would add 1 coral resource to the most expensive available column (e.g., Column 4).
  • Example 2: If the event card says, “Shark loses 1 fish,” the player controlling the Blacktip Reef Shark must immediately discard 1 fish token.

Example Situation:
If you take the last resource from Column 1 (which costs 1 energy), you must:

1. Pause your turn.
2. Draw two event cards.
3. Choose one event card to resolve (e.g., “Add 2 food” or “All players lose 1 energy”) and return the other to the deck.

After resolving the event, you resume your turn.

Ending the Game

The game ends when:

1. All resources from the reef bank are depleted, or
2. After 10 rounds (each player has taken 10 turns)—whichever occurs first.

Scoring:

• Blacktip Reef Shark tokens count as 2 points each.
• All other fish tokens count as 1 point each.

If there is a tie, the player with the most energy left wins. If energy is also tied, the player with the most leftover resources (water, coral, food, warmth combined) wins.

Game Bits

1x d10 (note: for reproduction subtract the number obtained on d-10)

1x d “2-4” (can use a d6 where 1 and 2 = 2, 3 and 4 = 3, and 5 and 6 = 4), or cover the other numbers on the d6.

1x d8

1x normal d6

Energy tokens

Reef resources (coral, food, clean water, and warmth)

Ocean “bank”

Reef board

Fish tokens for each species

Species cards, nursery cards, and “on your turn” action cards for each player

Assessment Goals

The main learning goals of Fish Reproduction are as follows:

• • Players will explore and understand what resources coral reefs need to thrive.

• Players will understand that energy is the “core resource” of ecosystems, and functions a little like money in the webs that make up communities and in individual populations. 

• Players will recall information about the Banggai cardinalfish, blacktip reef shark, striped poison-fang blenny, and humphead parrotfish—how they reproduce and how these different kinds of fish use and balance resources in an ecosystem

• Players will practice making strategic decisions about the use of limited resources, trying to balance short-term needs with long-term survival in their choices (similar to real-world sustainability issues in coral reef ecosystems)

• Players will understand specific issues affecting Indonesian reefs, like coral bleaching, pollution, and overfishing, through the event cards

• Players will experience how ecological events —like storms, pollution, or coral bleaching—can affect species survival by changing resource access (encouraging adaptability and problem-solving in the game, and for real fish!).

• Players will engage in competition for resources generally and in specific forms of ecologically relevant competition via event cards, reflecting how species interact in real ecosystems.

Assessment Strategies:

We engaged mostly with pre- and post-questions, but ended up changing them each playtest.

Generally, we asked:

What are some key resources that coral reefs need to survive and thrive?

What species do you know that might live in an Indonesian coral reef ecosystem?

How do fish reproduce? What are different ways that fish reproduce?

What are the advantages and disadvantages of different types of fish reproduction?

We’d likely need to run some more playtests before determining if this learning was really achieved in the game. However, we did have one playtester tell us that they felt this was a great learning tool. Additionally, most playtesters A. Could name a form of fish reproduction at the end of the game, B. Could name four factors that influence reef health, and C., Could list 1-3 potential events that may impact an Indonesian reef’s health.

One playtester also told us that she was unlikely to forget that volcanic eruptions can actually benefit distant corals by producing ash clouds that cool ocean surface temperatures. She remembered that this would reduce food availability (due to reduced photosynthesis) but be good for corals since corals aren’t responding well to increased warmth. So that was cool and very specific!

History Versions of Game

Version 1: Initial Concept

The first version of Fish Reproduction introduced the core mechanics, focusing on species-specific reproduction, resource gathering, and population growth. Players selected one of four species and collected resources from the reef bank to increase their fish populations. While the foundation was set, there were several challenges that emerged during playtesting.

Core Mechanics:

• Objective: Grow the largest fish population by collecting resources and reproducing. The player with the most fish tokens at the end of the game wins.
• Gameplay:
  • Resource Collection: Players collected one resource per turn from the reef bank without any cost or limitations.
  • Reproduction: Players spent resources to reproduce based on their species card, gaining additional fish tokens.
  • Event Cards: Players could trigger event cards to impact resources or other players.
  • Species-Specific Reproduction: Each species had distinct reproduction needs and outcomes (e.g., Blacktip Reef Shark required 2 food and 2 warmth).
  • End of Game: The game ended after a set number of rounds or when the reef bank was depleted.

Key Challenges:

• Lack of Strategy: With no cost for resource collection, there was limited strategic depth.
• Slow Pacing: The absence of resource costs made the game progress slowly, as players easily gathered resources.
• Imbalance: Starting position gave an advantage to some players, and reproduction mechanics were unbalanced, favoring certain species.
• Limited Interaction: The game felt isolated, with minimal player interaction and competition.

Playtest Feedback (Playtest 1): (Playing within group, then group of young adults in class/classmates)

• Race to Finish: The game felt more like a race once players understood the mechanics, with little focus on managing resources.
• No Penalties: The lack of resource costs made the game less engaging and removed penalties for poor decision-making.
• Too Random: Players felt there was little strategy involved, and outcomes appeared too random.

Changes for Version 2:

• Introduced energy dynamics to add strategic decision-making to resource collection.
• Rebalanced species to ensure fairness in resource requirements and reproduction outcomes.

Version 2: Strategic Depth with Energy Dynamics

Version 2 addressed the lack of strategy by introducing energy costs for collecting resources. This added a layer of decision-making, forcing players to balance energy use and resource gathering. The changes encouraged players to plan ahead and conserve energy for reproduction.

Key Changes:

• Energy Costs: Each resource in the reef bank now had an energy cost (1 to 5 energy), adding strategic depth to resource collection.
• Resource Management: Players faced trade-offs between collecting resources and sacrificing fish tokens for energy, introducing more meaningful choices.
• Reproduction Balancing: Reproduction yields were balanced to ensure fairness across species, with each resource equally required for all species.
• Mathematical Tweaks and Simulations: Simulations (10,000 Monte Carlo and 40 ChatGPT-01 runs) ensured that the win rates of species were between 24% and 26%, creating a balanced experience.

Playtest Feedback (Playtest 2): (in GSB game group, with a group of 4 players of regular game nights!)

• Monotony: Despite improved strategy, the game still felt repetitive with little player interaction.
• Exclusion: Randomness in resource availability made some players feel left out, and the energy system, while better, lacked excitement.

Changes for Version 3:

• Increased Event Frequency: More frequent event card triggers to disrupt gameplay and increase competition.
• Smaller Reef Bank: Reduced the size of the reef bank to increase the tension and speed up rounds.

Version 3: More Events and More Interaction

Version 3 focused on increasing player interaction and adding variability through event cards. Events were triggered more frequently, affecting resources, energy, and player actions. This version aimed to make the game more competitive and dynamic.

Key Changes:

• Event Cards: Events were triggered whenever a column in the reef bank was emptied. Players drew two event cards and chose one to play, adding unpredictability and opportunities to impact other players.
  • Event card list
• Smaller Reef Bank: The reduced reef bank size sped up resource depletion and made rounds faster and more competitive.
• Final Balancing: New event cards and reproduction outcomes were balanced to ensure no species had an unfair advantage.

Playtest Feedback (Playtest 3 and 4): (in class)

• Increased Competition: Players appreciated the added tension from event cards, but requested more control over when events were triggered.
• Faster Rounds: The smaller reef bank helped speed up rounds, but resources still felt too abundant, and rounds were longer than desired.

Version 4: Final Balancing and Event Frequency

Version 4 is the final iteration of Fish Reproduction, focusing on refining event card mechanics and ensuring quicker resource depletion. This version also introduced more frequent events to keep gameplay dynamic and competitive while providing greater flexibility in reproduction.

Key Changes:

• Increased Event Frequency: Events now trigger more often, impacting resources and competition between players more frequently.
• Event Cards and Energy: The incentive for triggering events by collecting energy was made random, adding more excitement.
• Reproduction Flexibility: Players could now reproduce multiple times per turn, creating more strategic options.
• Game End: Version 4 introduced a round limit, ending the game after a set number of turns rather than solely relying on resource depletion.

This final version successfully addressed the major concerns raised during playtesting and hopefully brought the game to a well-balanced, competitive state.

Reflection on the Final Version of Fish Reproduction

The final version of Fish Reproduction is the result of several rounds of testing and refining, and it now offers a more balanced and interactive experience. Throughout the development process, player feedback was key in shaping the game’s mechanics, dynamics, and overall feel. Each playtest highlighted areas that needed improvement, and changes were made to create a more strategic and engaging game.

Mechanics:

The mechanics of the game are now focused on giving players meaningful choices. Adding energy costs to resource collection forced players to think carefully about how they manage resources, instead of just gathering them freely. Players must now balance when to gather resources, reproduce, or sacrifice fish for energy, making each turn more impactful. The event card system also adds unpredictability, keeping players on their toes and making sure that no game is the same.

Dynamics:

The dynamics have improved dramatically with the introduction of energy management and event cards. Players are now constantly making decisions that affect both themselves and others, creating a more competitive atmosphere. The reduced reef bank size ensures that resources run out faster, increasing the pressure and forcing players to react more quickly to changes. This keeps the game moving and ensures that players stay engaged throughout.

Aesthetics:

The aesthetics of the game aim to provide a mix of challenge, discovery, and interaction. Players enjoy the challenge of competing for limited resources and managing their species in a fragile ecosystem. The educational aspect of the game—learning about fish reproduction and ecosystems—is also well integrated, adding an element of discovery that players appreciate. Indirect interaction through resource competition and event cards fosters a sense of connection between players without making the game overly aggressive.

 

Overall, the final version of Fish Reproduction offers a better balance between strategy and engagement. The mechanics now require players to think ahead, the dynamics encourage meaningful competition, and the aesthetics make the game enjoyable while also providing educational value. Through multiple iterations, the game has evolved into a much more engaging experience for players of all levels.

Appendix – Game Balancing Math

Photos/Video Clips of Game Testing

Photos/Video Clips of Game Testing

 

Playtest Overviews

 

Note: Some of the informed changes are summarized in the section above

 

Playtest 1

• Number of players: 3
• Demographics: P1 Team (2 Male, 1 Female, Ages: 21-27)

Summary of Feedback:
In the initial playtest, players felt the game lacked penalties for resource gathering, which made it feel less strategic. They also noted that the game became a “race to the finish” without much focus on resource management. The absence of energy dynamics reduced strategic depth, and players mentioned that outcomes felt too random.

Informed Changes:

• Introduced energy dynamics to add more strategic decision-making to resource gathering.
• Rebalanced species mechanics to ensure fairness in reproduction and resource requirements.

Playtest 2

• Number of players: 4
• Demographics: CS377G Students (2 Male, 2 Female)

Summary of Feedback:
While informative, the gameplay lacked balance. Players suggested the need to balance numbers, improve event card mechanics, and introduce a sustenance component. Additional clarity was needed around what actions could happen per turn, and the size of the resource bank required adjustment.

Informed Changes:

• Introduced energy costs (1 to 5 energy) for collecting resources to add more strategic depth.
• Introduced resource management trade-offs, where players had to choose between gathering resources or sacrificing fish for energy.
• Rebalanced reproduction yields to ensure fairness across species and equal demand for all resource types.
• Conducted mathematical simulations (10,000 Monte Carlo and 40 ChatGPT simulations) to ensure balanced win rates across species.

Playtest 3

• Number of players: 5
• Demographics: Stanford MBA Students (3 Male, 2 Female, Ages: 26-32)

Summary of Feedback:
Although the new strategy improved gameplay, players still felt the game was repetitive with little player interaction. Randomness in resource availability left some players feeling excluded, and while the energy system was better, it lacked excitement.

Informed Changes:

• Reduced the reef bank size to speed up resource depletion and increase competition.
• Made event cards a central mechanic to introduce more unpredictable changes and interactions.

Playtest 4

• Number of players: 4
• Demographics: CS377G Students (2 Male, 2 Female)

Summary of Feedback:
Players requested more competition and randomness, such as resource stealing. Resources didn’t run out quickly enough, and the Shark player felt left out because they couldn’t roll. Despite this, players reported learning about fish reproduction, and the market and energy-trading mechanics worked well.

Informed Changes:

• Gave players more control over event cards, allowing them to be triggered through energy-related actions, adding excitement and randomness.
• Increased flexibility for reproduction, enabling players to reproduce multiple times per turn for more strategic choices.

Playtest 5

• Number of players: 4
• Demographics: CS377G Students (2 Female, 2 Male, Ages: 19-23)

Summary of Feedback:
Players appreciated the competitive and strategic nature of limited resource purchasing, but those who fell behind found it frustrating to catch up. Event choices were well-received for adding interaction, but players felt the rules were unclear, particularly regarding turn actions. Participants also suggested that moderators step back and let them figure out the game on their own.

Informed Changes:

• Rewrote the rules to clarify turn actions, and added example cards for easier reference.
• Increased player agency by allowing more flexible actions per turn, addressing concerns about frustration for players who fell behind.

 

Link to a “Print at Home” Version

This link (81 MB)  contains the files for all digital assets, including the Reef + Ocean (the game board), the event cards, the back of the event cards, and the rules book. This link contains the printable fish species cards, fish “nurseries” for keeping your population, and printable turn cards (all designed to be affixed to 3×5 index cards) plus the fish tokens and resource chips. Print everything and cut out tokens, grab your dice, and you are all set!

 

Backup link: Fish Reproduction Board Game.pdf