How to use PlayDSA
PlayDSA teaches the data structures and algorithms behind coding interviews by making you play them. Here's everything you need to know.
1. Getting started
- Meet Bit. On first launch, pick a name (optional), a colour for your buddy Bit, and a small daily goal. It takes under a minute and needs no account.
- Open the Learn tab. Swipe through the floating worlds. Start with World 1 · Array Alley.
- Tap a level on the world map. Levels unlock one after another. Clearing every level in a world opens the next one.
2. The level loop: learn → play → remember
- Lesson. Bit explains one idea in four short steps: the big idea, the moves, how fast it is, and the code. Switch the code between Python, JavaScript, TypeScript and C++.
- Pick a difficulty.
- Easy: 5 energy, small inputs and helpful labels.
- Medium: 3 energy and bigger inputs.
- Hard: 2 energy, the biggest inputs and hidden helpers. XP ×3.
- Play the mission. The camera flies into the 3D arena and shows your objective. Perform the algorithm one move at a time.
- Debrief. Earn stars and XP, collect a skill card, and practise the same pattern on the linked LeetCode problems.
3. Controls
| Action | How |
|---|---|
| Make a move | Tap the big buttons at the bottom (e.g. Swap, Push, Merge), or tap a crate, node or tile in the scene when the prompt says so. |
| Look around | Swipe left or right on the 3D scene. The camera springs back when you let go. |
| Read the tags | Glowing tags above objects show the pointers: L, R, i, j, pivot, slow, fast and so on. |
| Energy | The bar at the top right. Each wrong move costs one cell. Run out and you can retry with a fresh puzzle. |
| Leave | The ✕ at the top left (or your phone's back gesture). |
Feedback from Bit appears at the top of the screen. Correct moves chime, and a run of three or more shows a COMBO. A wrong move shakes the screen and Bit explains why it was wrong. That explanation is the lesson, so read it!
4. Stuck? Use hints
- Tap the 💡 bulb for a hint about the current step.
- Still stuck? Tap Show me the move and Bit plays one correct step for you, so you can watch it happen.
- Using a hint caps that run at 2 stars. Hints are for learning, so use them freely, then replay for 3 stars.
5. Stars and XP
| Stars | How to earn them |
|---|---|
| ★★★ | No mistakes and no hints |
| ★★ | One mistake, or a hint used |
| ★ | Finished with more mistakes |
XP depends on stars and difficulty (×1 Easy, ×2 Medium, ×3 Hard). Your XP raises your rank, from Novice all the way to Grandmaster. Once you master a difficulty, Bit suggests the next one, so the challenge stays just right.
6. Streaks, daily goal and reviews
- Daily goal: a small XP target you choose (change it in Me). The ring on the home screen fills as you play.
- Spark streak: play on consecutive days to grow it. Every 7 days earns a shield that covers one missed day. No guilt, no pressure.
- Rusty skills (spaced repetition): cleared levels come back for review after 1, 2, 4, 7, 15 and 30 days. A quick replay when a skill is due gives bonus XP and moves the next review further out. This is how the patterns move into long-term memory.
7. Practice modes (Play tab)
| Mode | What it is |
|---|---|
| Daily Challenge | One puzzle per day, the same for everyone. +50 XP. |
| Blitz | 60 seconds of rapid-fire questions. Three in a row doubles your points. |
| Shuffle | A random level you've already cleared, with a brand-new puzzle. |
| Interview Arena | Read a problem and name the pattern, the skill that cracks real interviews. |
8. Study tips that actually work
- Little and often. 15 minutes a day beats a 3-hour weekend cram.
- Say the rule out loud before each move ("sum too small, so move L right"). It makes the pattern stick.
- After each level, solve one linked LeetCode problem while the idea is fresh.
- Replay on Hard once Medium feels easy. Bigger inputs force you to trust the pattern.
- Do your reviews when skills get rusty. Recalling something just as you're about to forget it is what makes memory last.
9. FAQ
Do I need an internet connection?
No. PlayDSA works completely offline. You only need a connection to open the optional LeetCode links.
Will I lose my progress if I change phones?
Progress is stored only on your device. Your phone's own backup may restore it on a new device, but PlayDSA has no cloud account.
How do I start over?
Go to Me → Reset progress. Your name and buddy are kept; stars, XP and streak are cleared.
Is PlayDSA for complete beginners?
Yes. World 1 starts from zero, and Easy mode adds labels and extra energy. It also goes far enough (Dijkstra, Union-Find, DP, backtracking) to be useful right up to interview day.
I found a bug or have an idea.
We'd love to hear it: hello@sterin.dev, or tap Me → Help & feedback in the app.