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How to create a luck system in Scratch games

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GD

GameDevPro88

Posted on June 18, 2022 • Intermediate

🎲 Help with luck/rarity system

Hey everyone! I’m working on a mining game where players can find different types of apples with varying rarity levels. I want to create a proper luck system where:

  • Common apples appear frequently (like 60% chance)
  • Rare apples appear sometimes (like 25% chance)
  • Epic apples are uncommon (like 10% chance)
  • Mythical apples are super rare (like 5% chance)

I’ve been using the “pick random” block, but my rarest items keep showing up too often! What am I doing wrong? Any tips for creating balanced probability systems? 🤔

RM

RandomMaster_Dev

Replied 1 hour later • ⭐ Best Answer

Great question @GameDevPro88! The key to a good luck system is understanding how to properly use weighted probability. Let me show you the right way to do this:

🎯 Understanding Probability Ranges

Instead of separate random checks for each item, use one random number and check ranges:

flowchart TD A[🎲 Pick Random 1 to 100] --> B{Check Result} B -->|1-60| C[🍎 Common Apple<br/>60% chance] B -->|61-85| D[🍏 Rare Apple<br/>25% chance] B -->|86-95| E[✨ Epic Apple<br/>10% chance] B -->|96-100| F[🌟 Mythical Apple<br/>5% chance] C --> G[🎮 Give Item to Player] D --> G E --> G F --> G style A fill:#e1f5fe style C fill:#e8f5e8 style D fill:#fff3e0 style E fill:#f3e5f5 style F fill:#fce4ec

🔧 Proper Implementation

Here’s the correct way to code your luck system:

    when flag clicked
forever
if <key [space v] pressed?> then
mine apple
end
end

define mine apple
set [luck roll v] to (pick random (1) to (100))
if <(luck roll) ≤ [60]> then
set [found item v] to [Common Apple]
change [common apples v] by (1)
else
if <(luck roll) ≤ [85]> then
set [found item v] to [Rare Apple]
change [rare apples v] by (1)
else
if <(luck roll) ≤ [95]> then
set [found item v] to [Epic Apple]
change [epic apples v] by (1)
else
set [found item v] to [Mythical Apple]
change [mythical apples v] by (1)
end
end
end
say (join [Found: ] (found item)) for (2) seconds

⚠️ Common Mistakes to Avoid

❌ Wrong Way (Multiple Random Checks):

    // DON'T DO THIS - it breaks probability!
if <(pick random (1) to (100)) ≤ [5]> then
set [item v] to [Mythical]
else
if <(pick random (1) to (100)) ≤ [10]> then
set [item v] to [Epic]
else
// This creates wrong probabilities!
end
end

✅ Right Way (Single Random Check):

Always use ONE random number and check it against cumulative ranges!

🎮 Advanced Luck Features

Want to make it even more interesting? Try these additions:

1. Luck Multipliers

    // Increase luck based on player level
set [luck bonus v] to ((player level) / [10])
set [mythical chance v] to ([5] + (luck bonus))

// Use in your probability check
if <(luck roll) > ([100] - (mythical chance))> then
set [found item v] to [Mythical Apple]
end

2. Pity System (Guaranteed Rare After X Attempts)

    // Track attempts without rare item
change [attempts since rare v] by (1)

// Force rare item after 20 attempts
if <(attempts since rare) ≥ [20]> then
set [found item v] to [Epic Apple]
set [attempts since rare v] to [0]
else
// Normal luck system here
end

3. Dynamic Rarity (Seasonal Events)

    // Double mythical chance during special events
if <(special event) = [true]> then
set [mythical threshold v] to [90]  // 10% instead of 5%
else
set [mythical threshold v] to [95]  // Normal 5%
end

This approach ensures your rarity system works exactly as intended! 🎯

GD

GameDevPro88

Replied 2 hours later

@RandomMaster_Dev This is EXACTLY what I needed! 🤩

I was doing multiple random checks which totally messed up my probabilities. No wonder my mythical apples were showing up way too often! The single random number approach makes so much sense.

Already implemented it and the rarity distribution looks perfect now. Thank you so much! 🙏

LG

LootGuru_Maya

Replied 3 hours later

Adding to this excellent explanation! Here’s a pro tip for testing your luck system:

    // Debug mode to test probabilities
when [d v] key pressed
repeat (1000)
mine apple
end
say (join [Common: ] (common apples))
wait (1) seconds
say (join [Rare: ] (rare apples))
wait (1) seconds
say (join [Epic: ] (epic apples))
wait (1) seconds
say (join [Mythical: ] (mythical apples))

Run this 1000 times and you should see roughly: Common ~600, Rare ~250, Epic ~100, Mythical ~50. If the numbers are way off, check your probability ranges! 📊

PS

ProbabilityStudent_Jake

Replied 5 hours later

This thread is gold! 🏆 I’m working on a card game and was struggling with the same issue. The weighted probability approach works perfectly for card rarity too!

For anyone else working on similar systems, you can also use this for:

  • 🎰 Slot machine outcomes
  • 🎁 Loot box contents
  • 🌟 Critical hit chances
  • 🎲 Random event triggers

Thanks for sharing the knowledge! 🤓

VB

Vibelf_Community

Pinned Message • Moderator

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