Think you can outsmart a sentient sack?
Your backpack is hungry for treasures! Pack the most valuable items without overloading it. Solve puzzles, conquer arenas, and compete with players worldwide.
How It Works
Simple to learn, endlessly challenging. Based on the famous knapsack problem from computer science.
Meet the Items
Each item has a value and a weight. Pick the ones worth the most!
Tap to Select
Tap tiles to add items to your backpack. Watch the capacity bar fill up.
Watch Your Weight
Don’t exceed your backpack’s capacity! Green means go, red means stop.
Earn Stars
Find the optimal value to earn up to 3 stars. Fewer attempts = more stars!
Try It Right Now
This is a real knapsack puzzle. Select items to maximize value without exceeding the weight limit. Can you find the perfect solution?
Game Modes
Four ways to play. Whether you want a chill adventure or a competitive rush, there's a mode for you.
Adventure
CampaignExplore 5 themed arenas across 60 puzzles. From Grasslands to Summit, each arena gets harder. Defeat bosses to unlock the next world.
Daily Quiz
CompetitiveOne puzzle per day, same for everyone worldwide. Race against the clock, climb the global leaderboard. Can you be the fastest?
Time Attack
EndlessHow many puzzles can you solve before time runs out? A fast-paced endless mode that tests your speed and accuracy.
My Nap'Sac
CollectionSpend your hard-earned stars to collect adorable Nap companions. Build and expand your world with ponds, trees, and more.
Why You'll Love It
Nap'Sac blends brain-teasing puzzles with a playful adventure that keeps you coming back.
Train Your Brain
Based on the NP-complete knapsack problem. Every puzzle is a unique optimization challenge.
Global Competition
Same daily puzzle for everyone. Compete for the top spot on the worldwide leaderboard.
Themed Arenas
Journey through Grasslands, Forge, Inferno, Crystal Caves, and Summit.
Star System
3 stars for first-try perfection. Collect them all to unlock new content.
Dark Mode
Play comfortably day or night with full dark mode support.
11+ Languages
English, French, German, Spanish, Japanese, Korean, Chinese, and more.
Meet the Characters
Your backpack has many moods. Collect them all in My Nap'Sac!
Ready to Pack?
Download Nap'Sac for free and start your puzzle adventure today. Prove you're smarter than a backpack!