🐟 Planning Workbook: Fishy

How to use this workbook: work top to bottom. It walks you through planning Fishy with the method from 01-How-to-Plan-a-Game, then gives you a build order. It says what each piece is and which technique to reach for — you open the Technique Playground and write the code. Wherever you see ✍️ YOUR TURN or a checkbox, that's your work.

The game in a nutshell

You're a small fish in the sea. Swim around and eat fish smaller than you to grow bigger. But watch out — fish bigger than you will eat you. The bigger you grow, the more of the ocean becomes your lunch.

This game's special new idea is size that changes — your fish grows, and size decides who eats whom.

Step 1 — Say it in one sentence

Starting version — ✍️ YOUR TURN: make it yours.

"Swim around eating smaller fish to grow, while dodging fish bigger than me."

Step 2 — What's on the screen? (objects)

• Player fish — you. (a circle, or a circle + a little triangle tail)
• Other fish — lots of them, in different sizes. (circles of different sizes/colors)
• Score / size text — the HUD.
• The sea — a background color.

✍️ YOUR TURN: decide your shapes and colors. A neat trick: color fish by how dangerous they are (green = smaller than you, red = bigger than you). You could add that later.

Step 3 — What does each object DO? (behaviors)

✍️ YOUR TURN: fill in the blanks.

• Player fish: moves where you steer it, and __________ when it eats.
• Other fish: __________ across the screen, then disappear when they swim off the far side.
• New fish: keep __________ over time so the sea never runs empty.

Step 4 — The rules ("when ___, then ___")

The heart of Fishy is a size comparison. Fill in the blanks.

• When the player touches a fish that is smaller → __________ it, grow a little, +score.
• When the player touches a fish that is bigger → __________________________.
• Every so often → spawn a new fish at a random size and position.

🔑 Key insight: every fish (including you) needs to know its own size as a number. The whole game is really just: "compare my size to the fish I touched — bigger number wins."

Step 5 — States (scenes)

Title → Playing → Game Over (eaten by a bigger fish) → back to Title.

✍️ YOUR TURN — DECISION: is there a win, or is it endless (go for a high score)? Two good options:

• Endless: never "win" — just survive and grow for the highest score.
• Goal size: reach a target size (e.g. the biggest in the sea) and you Win.

Pick one. (Technique 11 covers scenes.)

🧩 Your Architecture Map

Two rows filled in as examples. ✍️ YOUR TURN: complete the rest.

Notice the player has a scale component — that's the growing part (Technique 13).

🏗️ Build order (your milestones)

Build one at a time. Run and check the "✅ works when" line before moving on.

Milestone 1 — Your fish swims

Put the player fish on screen and let it move. Fishy is a free-swimming game (no maze, no gravity), so this is the simplest movement of the three games.

• 🤔 DECISION — how do you steer? Pick one:
  • Arrow keys / WASD: move up/down/left/right (Technique 4 + 5).
  • Follow the mouse: the fish swims toward your cursor (Technique 5 shows a "move toward a point" trick, and Technique 14 uses the same idea).
  • Try one; you can switch later.
• ✅ Works when: you can swim your fish around the screen.
• 🔧 Techniques: 1, 2, 4, 5

Milestone 2 — The sea fills with fish

Spawn other fish over time (Technique 9). Each new fish should:

• appear at a random position on one side,

• have a random size (store that size as a number!),

• drift to the other side, and

• get removed when it swims off-screen (Technique 9's off-screen cleanup).

• ✅ Works when: fish keep appearing and drifting across, and old ones vanish off the edge (they don't pile up forever).

• 🔧 Techniques: 9, 5, plus 3 for tagging them "fish"

Milestone 3 — Eat the smaller fish

Give the player an onCollide with the "fish" tag (Technique 8). In the collision, compare sizes: if the other fish's size number is smaller than yours, eat it (destroy it) and add to your score (Technique 12).

• 🔑 This is where your "every fish knows its size" plan pays off. The comparison is the whole game.
• ✅ Works when: swimming into a smaller fish makes it disappear and scores; swimming into a bigger one does nothing yet (that's the next milestone).
• 🔧 Techniques: 8, 12

Milestone 4 — Grow when you eat

Each time you eat, make the player a little bigger (Technique 13 — growing with scale). Also bump the size number you compare with, so as you grow you can eat bigger and bigger fish.

• 🤔 DECISION: how much do you grow per fish? A tiny bit each time feels smooth; too much and you win instantly. Tune it by testing.
• ✅ Works when: eating fish visibly grows your fish, and you can then eat fish you couldn't before.
• 🔧 Techniques: 13

Milestone 5 — Getting eaten ends the game

Now handle the other half of the size comparison: if the fish you touch is bigger than you, it's game over (Technique 11).

• ✅ Works when: touching a bigger fish sends you to a Game Over screen, but smaller fish still get eaten.
• 🔧 Techniques: 8, 11

Milestone 6 — Title, Game Over, and score

Wrap it in scenes: a Title screen ("Press SPACE to swim"), and a Game Over screen that shows your final size/score and lets you restart. If you chose a goal size, add the Win scene too.

• ✅ Works when: the game has a start screen, plays, ends, and restarts — the full loop.
• 🔧 Techniques: 11, 12

🌟 Stretch goals (only after it works!)

• Danger colors: tint each fish green if it's smaller than you and red if it's bigger, updated as you grow. (Great use of checking sizes every frame.)
• Fish that react: small fish flee from you; big fish chase you (Technique 14 — same "move toward/away from a point" idea).
• A gulp sound when you eat (Technique 15).
• A "you're the biggest fish in the sea!" win when you reach the top size.
• Face the fish left or right depending on swim direction.
• Swap the circles for real fish sprite images (Technique 2).

✅ Fishy planning checklist

• I filled in the Architecture Map (all rows).
• I understand every fish needs a size number, and the game compares sizes.
• I decided my controls (keys vs mouse).
• I decided endless vs goal-size (win or no win).
• I know my lose condition (touched a bigger fish).
• I have my milestone list and I'm building one at a time.

Start with Milestone 1 — get your fish swimming. Then let the sea fill up. 🌊