NumNull | Collapse to Null

NumNull is a Flutter-based web game built around a deceptively simple idea: given a grid of integers (ranging from -9 to +9, never 0), use addition and subtraction to collapse tiles into zero. A tile reduced to zero becomes a Null (Ø) — the game's core currency and victory condition.

The challenge lies in efficiency. You're scored not just on how many Nulls you create, but how few moves and how little time you take to create them. This makes NumNull simultaneously a math puzzle, a strategy game, and a speed challenge.

NumNull supports solo play (Casual), head-to-head competition (Competitive), and friend-created custom games (Custom) — each with Arcade and Classic variants.

Getting Started

Sign Up / Authentication

NumNull uses Google Sign-In for authentication. When you sign in with Google, your profile (display name, avatar) is tied to your account and visible on leaderboards.

Ghost Mode

If you prefer not to share your personal details, you can play as a Ghost. Ghost accounts are fully functional — you can play games, earn XP, and appear on leaderboards — but they are not recoverable.

CRITICAL WARNING: If you log out as a Ghost, your account and all associated progress are permanently lost. There is no way to retrieve a Ghost account after logout.

Dashboard

The main dashboard gives you access to everything in one view. The interface features a dark grid backdrop, clean glassmorphic panels, and neon-themed cards.

Section	Description
Modes	Launch Casual, Competitive, or Custom games
Leaderboard	Browse top players globally or by country
Reward	Claim your daily login reward and view your streak consistency
Store	Purchase power-ups (Undo, Sign Change) and Bits
Activity	View your recent game history, including scores and match outputs

Your profile avatar, username, current Bits balance, and Null count are always visible in the top navigation bar.

Game Modes

Casual Mode

Practice

Casual mode is designed for learning and practice. There are no ranking stakes — it's a safe space to master tile mechanics, experiment with strategies, and understand how Nulls propagate.

You still earn XP and rewards for completing games, but there's no pressure of a live opponent.

Best for:

New players learning the rules
Practicing specific board sizes
Exploring Arcade power-up combos

Competitive Mode

Live Match

Competitive mode puts you against a real opponent in a live match. Both players are assigned the same board (same seed) and race to achieve the highest score within a 5-minute time limit.

Whoever has the higher score when time expires — or completes the board faster — wins.

Key features:

Matched boards (same starting configurations)
5-minute countdown timer
Real-time score comparison
XP and ranking rewards based on outcome

Custom Mode

Seed Based

Custom mode lets you create or join a game using a seed — a unique string that deterministically generates a specific board configuration. Share your seed with friends to challenge them.

No ranking impact — purely for fun, learning, and friendly competition.

Key features:

Enter any seed to generate a specific board
Share seeds for async or live challenges
Full control over board size and game type
Purely friendly, non-ranked matches

Game Types

Every game mode (Casual, Competitive, Custom) offers two game types that change how you play and your score output:

Arcade Type

Arcade mode enables power-ups that can be used strategically during gameplay to rescue a locked board or optimize your move count:

Undo — Reverse your last move.
Sign Change — Flip the sign of a tile (positive ↔ negative).

Power-ups are purchased from the Store using Bits. They add a layer of tactical depth, especially on larger boards where a single mistake can cascade.

Classic Type

Classic mode has no power-ups. Every move is permanent and must be planned carefully before execution. Classic games require higher precision.

No Undo capability — errors are permanent.
No Sign Change capability — must rely entirely on arithmetic.

Classic games typically yield higher XP rewards, as they demand greater skill, mathematical foresight, and precision.

Board Sizes

Both Arcade and Classic types support four board sizes, accommodating beginners through grandmasters:

Size	Grid Config	Difficulty Level
3	3 × 3 Grid	Beginner
5	5 × 5 Grid (Default)	Standard
7	7 × 7 Grid	Advanced
9	9 × 9 Grid	Expert

Larger boards increase complexity exponentially — more tiles mean more possible interactions, more strategic planning required, and higher potential XP. The Start button shows the Bit cost to enter that configuration before you confirm.

How to Play

The Board

The game board is an N×N grid populated with random non-zero integers ranging from -9 to +9.

-3-58-1-7

4Ø-77-1

3ØØ91

-5ØØØ-4

-568-6Ø

Example starting configuration mid-game (Ø represents created Null tiles).

Making a Move

To perform a move, follow these two steps:

Select any tile (it highlights).
Click an adjacent tile — the relative direction of your click determines the arithmetic operation:

Direction of Click	Arithmetic Operation	Axis Mapping
Up	Addition (+)	+Y axis
Right	Addition (+)	+X axis
Down	Subtraction (−)	−Y axis
Left	Subtraction (−)	−X axis

What happens after a move:

The first tile (selected first) is locked as 0. It turns grey, becomes inactive, and can no longer participate in future arithmetic operations or Null swaps.
The second tile (clicked toward) receives the **result** of the calculation:
- If the result is non-zero, the second tile's value updates to that result.
- If the result is exactly 0, the second tile collapses into a **Null (Ø)**.

5 + (−5) = 0

Select tile with value 5, then click the tile to the right with value -5:

First tile (5) → locked as 0 (inert)
Second tile (-5) → becomes a Null (Ø)

3 − 7 = −4

Select tile with value 3, then click the tile below it with value 7:

First tile (3) → locked as 0 (inert)
Second tile (7) → updates to -4

The Null Tile (Ø)

The Null tile (Ø) is the game's core goal and a powerful tactical tool. Once created, it behaves differently from normal numbers:

⭐

Wildcard movement: A Null tile can swap positions with any adjacent non-zero tile — including diagonally adjacent tiles.

🛡️

Non-destructive: Swapping a Null with another tile does not trigger any calculation. It is a purely positional move that uses up no numbers.

🚫

Selective: A Null can only swap with tiles holding a non-zero value. It cannot swap with locked zero tiles or other Nulls.

⚙️

Strategic tool: By repositioning Nulls, you can set up future calculations — bringing numbers together to trigger chain reaction zeros.

NumNull Mini-Simulator

Interactive Demo

Try the rules live! Select a tile, then click an adjacent tile. Tap the "Reset" button to start over.

5

-5

2

3

7

-2

Ø

-4

1

Moves 0

Nulls 1

Gameplay Log

Simulator ready. Select a tile to begin!

Tips to try:

Select the 5 (top-left) and click right (on -5) → 5 + (-5) = 0. Watch it create a new Null!
Select the 3 (middle-left) and click down (on Ø) → 3 - 0 is not a valid arithmetic move. (Nulls cannot be calculated on, only swapped!)
Select the Ø (bottom-left) and drag/click to 3 (diagonally or orthogonally) → Swaps places non-destructively!

Scoring & XP

Your score reflects mathematical efficiency and speed. In Competitive matches, higher efficiency leads to victory.

Factor	Impact on Score
Nulls Created	More Nulls increases your base score.
Moves Used	Fewer moves increases your efficiency multiplier.
Time Taken	Less time elapsed yields a higher speed multiplier.

XP Calculation

XP represents your permanent progress, which maps directly to your place on the global leaderboard. It is derived from your final game score using the formula:

XP = round(5 × √score)

This square root curve results in diminishing XP gains at extremely high scores, ensuring casual players progress steadily while master class games are rewarded fairly:

Game Score	XP Earned (Null Currency)
25	25 XP
100	50 XP
196	70 XP
400	100 XP
900	150 XP

Post-Game Stats

Every game reports a comprehensive suite of stats, enabling you to inspect your performance:

Total Nulls created (yours vs opponent's)
Moves used (yours vs opponent's)
Time taken (your speed vs opponent's)
Efficiency percentages
Moves per Null ratio & Average time per Null
XP earned (calculated from final score)

Star Ratings

After each game, you receive a performance-based rating tier:

Stars	Rating Tier
★☆☆☆☆	Amateur
★★☆☆☆	Mediocre
★★★☆☆	Expert
★★★★☆	Legend
★★★★★	God

Earning a 5-star rating (★★★★★) in Casual mode grants additional bonus rewards.

Currency & Economy

NumNull operates on a dual-token system separating game entries from ranking progression:

Bits

Premium Entry Currency

Used to start game sessions. Every board size and configuration carries a dynamic entry fee in Bits.

Earned through: Daily rewards, Store purchases

Used for: Game entries, Arcade power-up purchases

XP

Progress Currency

Represents your accumulated XP across games. These are non-spendable and represent your ranking.

Earned through: Completing games (higher scores = more XP)

Used for: Global and regional leaderboard rankings

Power-Ups (Arcade Only)

Power-ups are tactical modifiers purchasable from the store and usable exclusively in Arcade mode:

Power-Up	Description	Strategic Use
Undo	Reverses your most recent move, restoring both tiles to their previous values.	Allows recovery from accidental moves, miscalculations, or testing paths without commitment.
Sign Change	Flips the mathematical sign of any selected tile (e.g., 7 becomes -7, or -3 becomes 3).	Sets up a perfect zero-collapse without requiring a sub-optimal intermediate operation.

Daily Rewards

Consistent logins are tracked via a daily login streak that updates globally at 00:00 UTC:

📅

Streak Progression: Your login streak increases by 1 each day you log in, rewarding you with Bits. The higher your active streak, the greater the daily Bit payout.

UTC Reset: Streaks must be updated daily. The cutoff is midnight (00:00 UTC) sharp.
No Recovery: Missing a single day resets your streak back to 0. It cannot be recovered.
Bit Rewards: Daily claims award Bits based on your streak progression. Higher login streaks yield increasingly larger daily Bit rewards to fund your match entries.

Store

The in-game Store allows players to top up resources and stock up on tactical equipment. Access it from the cart icon on the main dashboard.

Bits Packs

Purchase entry credits in various bundles to keep playing boards of any size. Billed through your App Store or Google Play Store account:

80 Bits ₹100
256 Bits ₹300
512 Bits ₹500
1,024 Bits ₹1K

Power-Up Refills

Buy packs of Undo and Flip modifiers using your accumulated Bits to prepare for matches:

4 Undos 80 Bits
8 Undos 120 Bits
4 Flips 80 Bits
8 Flips 120 Bits

Purchases are tied to your primary Google account (or local profile in Ghost mode) and persist across sessions.

Leaderboard

The global rankings showcase the top players ordered by their accumulated XP (Nulls). Rankings update immediately post-match.

Global | Country-Specific (e.g. 🇮🇳 IN)

Rank Player Total XP (Ø)

1. 👑 🏴‍☠️ PIRATE 🇮🇳 1,692 Ø

2. 🪎 TREASURE 🇮🇳 1,293 Ø

3. 🐱 RUSTY 🇮🇳 1,118 Ø

Competitive matches yield the highest concentration of XP, but regular practice builds long-term rank.

Post-Game Summary

Upon completing any game session, the summary overlay provides detailed analysis of your performance compared to your opponent (if in Competitive mode):

Summary Field	Description
Game Result	Displays Won, Draw, or Lose output.
Mode & Size	Shows match config, e.g., `Competitive · Arcade · 5×5`.
Star Rating	Visual stars mapping to your performance bracket.
Nulls / Moves / Time	Detailed breakdown comparing your counts against your opponent.
Score Comparison	Final scores side-by-side to declare the winner.
Game Seed	The unique string to copy and share so others can replay the same board.
Efficiency Stats	Includes percentage of Nulls created, Moves/Null, and Time/Null ratios.
XP & Bits Earned	Progress and currency payouts added to your account.