Mechanics, Loops, and Systems

🔄 Quick Recall: In Lesson 2, you learned flow theory, the MDA framework, and created your game design document. Now let’s design the mechanics that bring your GDD to life.

Anatomy of a Core Loop

Every game, from Pong to Elden Ring, runs on loops. The core loop is what the player does every 30 seconds — and it needs to be satisfying on its own.

The Three-Element Loop:

Challenge → Action → Reward → (repeat)

Notice something: the reward from one cycle becomes the setup for the next challenge. In Tetris, clearing lines creates new space — which immediately fills with new blocks. The loop feeds itself.

Design the core gameplay loop for my game:

Game concept: [your concept from the GDD]
Genre: [type]
Target session length: [how long should one sitting last?]

For the CORE LOOP (repeats every 10-30 seconds):
1. What challenge does the player face?
2. What action does the player take?
3. What reward do they receive?
4. How does the reward set up the next challenge?

For the META LOOP (repeats every 5-15 minutes):
1. What medium-term goal drives the player?
2. What accumulates between core loops? (XP, resources, progress)
3. What milestone triggers satisfaction? (level up, unlock, story beat)

For the LONG LOOP (repeats every 30-120 minutes):
1. What keeps the player coming back session after session?
2. What major progression exists? (story chapters, new areas, skill trees)
3. What's the ultimate goal? (beat the game, reach max level, complete collection)

Test: Does the core loop work if you remove ALL art and sound? If yes, you have a solid mechanic.

✅ Quick Check: Why should the core loop work even without art and sound?

Because art and sound are polish — they enhance a good mechanic but can’t create one. Tetris with no graphics (just colored blocks on a grid) is still fun. A game with gorgeous art but a boring core mechanic is still boring. Test the mechanic first, polish it later.

Progression Systems

Progression answers the question: “Why should I keep playing?”

Four Progression Models:

Most successful games combine 2-3 models. Dark Souls uses skill mastery + character growth. Zelda uses narrative + collection.

Design a progression system for my game:

Game: [your concept]
Core loop: [from above]
Target playtime: [total game length]
Progression model(s): [pick 2-3 from: skill mastery, character growth, narrative, collection]

Design:
1. What does the player start with? (abilities, resources, knowledge)
2. What's the progression curve? (linear, exponential, branching?)
3. What are the milestone rewards? (new ability every X minutes)
4. What's the pacing? (how often does something meaningful unlock?)
5. How does progression change the core loop? (new actions, new challenges)
6. What prevents the player from feeling overpowered too early?
7. What prevents the player from feeling stuck?

Include a progression timeline: map what unlocks at 25%, 50%, 75%, and 100% completion.

Game Economy Design

If your game has any resources (money, materials, energy, ammunition), you have an economy. Economies that aren’t designed intentionally break fast.

The Source-Sink Model:

Sources create currency/resources (enemy drops, quest rewards, harvesting). Sinks remove them (buying items, upgrades, repairs, consumables). When sources exceed sinks, you get inflation — everything becomes too easy. When sinks exceed sources, you get frustration.

Design the economy for my game:

Game: [your concept]
Resources/currencies: [list what the player earns and spends]

For each resource:
1. Sources: Where does the player earn it? (list all methods)
2. Sinks: Where does the player spend it? (list all uses)
3. Flow rate: How much enters vs. exits per play session?
4. Is it balanced? (do sources and sinks roughly match over time?)

Additional:
- Is there a dual currency? (earned currency vs. premium currency)
- What prevents hoarding? (reasons to spend, limited inventory)
- What prevents running dry? (guaranteed minimums, safety nets)
- At what point in the game does the player feel "wealthy"?

Flag any potential balance problems: inflation, deflation, or dead-end states where the player can't progress.

A warning on dual currencies: Games with soft currency (earned through play) and hard currency (usually paid) walk an ethical line. The research shows that the fairest approach rewards spenders with convenience and cosmetics, not power — keeping progression enjoyable for non-spenders too.

Rapid Prototyping with AI

Don’t build the full game yet. Prototype one mechanic at a time.

Step 1: Paper prototype first. Use index cards, dice, or tokens to simulate your core mechanic. Play it yourself. Play it with someone else. Does it work? Is it fun?

Step 2: Digital prototype with AI coding help.

Help me create a minimal prototype for this game mechanic:

Mechanic: [describe the core mechanic you want to test]
Engine: [Godot / Unity / web browser]
Goal: Test whether this mechanic feels fun with minimal features

Requirements:
- Player can perform the core action
- Basic feedback (visual or text) when the action succeeds or fails
- Simple challenge that tests the mechanic (one enemy, one puzzle, one obstacle)
- No art needed — use colored rectangles and placeholder text
- Prototype should be buildable in 1-2 hours

Generate the code for this prototype. Prioritize feel over features.

Step 3: Iterate based on playtest results. Ask people to play your prototype and watch them (don’t help). Where do they struggle? Where do they disengage? Fix those problems, not the ones you imagined.

Exercise: Build Your Core Loop

1. Define your core loop using the three-element template (challenge → action → reward)
2. Test it on paper — can you simulate it with cards or dice?
3. If it works on paper, create a digital prototype using the AI coding prompt
4. Play the prototype 10 times. Is the loop satisfying every time?

Key Takeaways

• The core gameplay loop (challenge → action → reward) is the foundation — it must be fun in its simplest form
• Nested loops create depth: micro (seconds), medium (minutes), macro (hours) loops keep different timescale motivations active
• Progression systems (skill mastery, character growth, narrative, collection) answer “why keep playing?”
• Game economies use the source-sink model — imbalanced economies break games fast
• Paper prototype before digital prototype; test one mechanic at a time
• Dual currencies should reward convenience, not power, to maintain fairness

Up Next: In the next lesson, you’ll use AI to generate the visual and audio assets that bring your prototype to life — from concept art and sprites to original music and sound effects.