F&F Brain Duel — Product Requirements Document
Version: 2.0
Date: 2026-03-13
Status: Draft
Privacy Policy
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1. Overview
F&F Brain Duel is a competitive multiplayer brain-training party game for iOS. Players sit around a shared device (phone or tablet) and compete in turn-based rounds, each presenting a unique cognitive or visual puzzle. The first player to collect 5 “brain stars” wins the game.
The app is designed for casual social play — family game nights, friend gatherings, and group entertainment — requiring no external materials or accessories.
2. Target Audience
- Families and friend groups looking for a shared-device party game
- Ages 8 and up (challenges are visual and intuitive)
- Players who enjoy puzzles, trivia, and competitive games
- Groups of 2 to 4 players
| Device |
Players |
| iPhone |
2 |
| iPad |
Up to 4 |
The app automatically adapts its layout based on the device type — vertical two-player layout on phones, four-corner layout on tablets.
4. Languages Supported
- English
- Portuguese (pt-PT)
- Spanish (es)
Language can be changed at any time from the setup screen.
5. Visual Themes
Theme can be toggled at any time from the setup screen.
6. App Flow
Setup Screen → Game Screen → [Star Celebration] → [Victory Screen]
↑__________________Play Again____________________|
New Game → Setup Screen
7. Setup Screen
7.1 Purpose
Allows players to configure the game before it begins: who is playing and which challenges will appear.
7.2 Player Configuration
- Each player taps their zone (top/bottom on phone, corners on tablet) to register
- A modal prompts for a name (up to 12 characters)
- Each player is automatically assigned a unique avatar color
- Players can tap their zone again to edit their name
7.3 Challenge Selection
- All challenge types are shown as toggleable cards
- Players can turn individual challenges on or off
- “Select All” and “Deselect All” shortcuts are available
- A counter shows how many challenges are currently selected (e.g., “5 / 15”)
7.4 Validation
- At least 2 players must be registered
- At least 1 challenge type must be selected
- The “Start Game” button is disabled until both conditions are met
7.5 Additional Controls
- Rules button: Opens a modal explaining the full game rules
- Language selector: Switch between English, Portuguese, and Spanish
- Theme toggle: Switch between dark and light mode
8. Game Screen
8.1 Layout — Phone (2 Players)
- Player 1 zone at the top (rotated 180° to face them)
- Player 2 zone at the bottom
- Challenge card centered between players
8.2 Layout — Tablet (Up to 4 Players)
- Four corner zones, one per player
- Top-positioned players are rotated 180° so the screen faces them
- Challenge card displayed large in the center
8.3 Player Zone
Each player’s zone always shows:
- Their avatar (initial + color)
- Their name
- Their current star count (up to 5 stars needed to win)
- Their card inventory (up to 4 colored dots representing held cards)
- A “READY” button that pulses during the buzz-in phase
8.4 Timer
- A visual countdown bar is displayed on the screen edges for both players
- 10 seconds per round during the reveal and buzz-in phases
- Timer starts when the card is revealed
- If time expires, the round ends without a correct answer
9. Round Flow
Each round goes through the following phases:
Phase 1 — Tease
- The card back is shown to all players (displays challenge type name and icon)
- No timer is running
- A player taps the card to start the round
Phase 2 — Reveal
- The card flips to show the full challenge content
- The 10-second timer begins
- All eligible players can buzz in
Phase 3 — Buzz In
- The first player to tap “READY” becomes the active player
- Other players are locked out
- The timer continues counting down
Phase 4 — Answer
- The active player gives their answer out loud
- The card is tapped again to reveal the correct answer
- The group verifies if the active player was correct
Phase 5 — Adjudicate
- Correct answer: The active player receives a card of the challenge type
- If they now hold 2 cards of the same type, those cards combine into 1 brain star
- If their inventory is full (4 cards), they must discard one card before the star is awarded
- Wrong answer: The card is discarded, and the player is blocked for the next round (3+ player games only)
10. Scoring and Win Condition
Cards (Inventory)
- Correct answers add 1 card to the player’s inventory
- Inventory cap: 4 cards maximum
- Cards are color-coded by challenge type
Brain Stars
- Every time a player holds 2 cards of the same challenge type, those cards convert into 1 brain star
- Stars are permanent — they cannot be lost
- A player can hold a maximum of 5 brain stars
Winning
- The first player to collect 5 brain stars wins immediately
- The game transitions to the Victory Screen
Discard
- If a player wins a card while already holding 4, a discard modal appears
- The player selects 1 card to remove before the new card is added
Blocking (3–4 Players Only)
- A wrong answer blocks the player for the following round
- They cannot buzz in during the next reveal phase
- They are automatically unblocked at the start of the round after that
11. Challenge Types
11.1 Memory
Goal: Remember all the animals shown, then name them from memory.
- 5 animal images are displayed in a circle
- Players study the animals, then the images are hidden
- Players must recall and name all 5 animals (in any order)
- Answer revealed: names appear next to each image
11.2 Maze
Goal: Find which entry point leads to the center of the maze.
- A grid maze is displayed with 4 labeled entries: A, B, C, D
- Only one path connects an entry to the center
- Players must identify the correct entry letter
- Answer revealed: correct entry highlighted in green
11.3 Color
Goal: Find the one word displayed in its matching color.
- A 3×3 grid shows 9 color words (e.g., “Red”, “Blue”, “Green”)
- Each word is displayed in a color — 8 are mismatched, 1 is correct
- Words may be rotated for extra difficulty
- Players must identify which word matches its color
- Answer revealed: the correct cell is outlined in green
11.4 Duplicates
Goal: Identify the animal that appears twice.
- 13 animal images are scattered across the screen
- 12 different animals are used, plus 1 duplicate
- Images are rotated and slightly offset for visual variety
- Players must find which animal appears twice
- Answer revealed: the duplicate animals are highlighted
11.5 Frequency
Goal: Identify which icon appears most often.
- 15–21 icons of 4 different types are scattered across the screen
- Icons include shapes like hearts, gears, lightbulbs, bells, and others
- One icon type appears more frequently than the others
- Players must name the most frequent icon
- Answer revealed: most frequent icon is circled in green
11.6 Reveal
Goal: Identify the hidden animal as it gradually reveals itself.
- An animal image starts blurred and zoomed in, hiding its identity
- Over 10 seconds, the image slowly comes into focus and zooms out
- Players try to identify the animal as early as possible
- The earlier the correct buzz, the more impressive
- Answer revealed: image fully shown with animal name
11.7 Odd One Out
Goal: Find the single item in a 3×3 grid that does not belong.
- 9 animal or icon images are arranged in a 3×3 grid
- 8 items share a common rule or category; 1 is the outlier
- Players must identify which item breaks the pattern
- Answer revealed: the odd item is highlighted and the shared rule is displayed
11.8 Shadow Match - comming soon
Goal: Match a coloured animal image to its correct silhouette.
- A reference animal image is shown in full colour at the top
- Below it, a 2×2 grid shows 4 silhouette options labelled A–D
- One silhouette is the true shadow of the reference; the others are flipped, rotated, or scaled variants
- Players must identify the correct letter
- Answer revealed: correct silhouette cross-fades to the full-colour image with a green border; wrong options dim to 40% opacity
- Difficulty increases across three tiers (easy/medium/hard) based on how similar the distractors are
11.9 Pattern Sequence - comming soon
Goal: Predict the missing shape in a visual sequence.
- A row of 4 coloured shapes is displayed (circles, squares, triangles, or stars), followed by a “?” placeholder
- Three answer options (A, B, C) show candidate shapes
- The sequence follows a hidden rule — shape cycle only (easy), shape + colour alternation (medium), or three-attribute progression (hard)
- Players must select the shape that comes next
- Answer revealed: correct shape slides into the “?” slot; a rule caption explains the pattern
11.10 Quick Math Splash - comming soon
Goal: Compare groups or solve a simple arithmetic challenge.
- Three sub-modes, determined by difficulty tier:
- Comparison (easy): Two groups of icons side by side — players identify which group has more
- Addition (medium): Two icon groups are shown; players pick the correct total from 3 numeric options (A, B, C)
- Balance (hard): A stylised balance scale shows two sides with icons and weights; players identify the heavier side
- Answer revealed: winning side highlighted in green; for addition, correct option turns green
11.11 Mirror - comming soon
Goal: Identify the correct horizontal mirror reflection of an animal image.
- A reference animal image is shown on one side
- A 2×2 option grid (A–D) shows four transformations of the same image: horizontal flip, vertical flip, 180° rotation, and the unchanged original
- Players must identify which option is the true horizontal mirror
- Answer revealed: correct option is highlighted with a green border; a mirror-line animation draws between the reference and the correct answer
11.12 Rapid Categories - comming soon
Goal: Find the one animal in a 2×3 grid that does not belong to the shown category.
- A category label is displayed (e.g., “Mammals”, “Can Fly”, “Ocean Animals”)
- 6 animal images are shown in a 2×3 grid; 5 belong to the category, 1 is the intruder
- Players must identify which animal does NOT belong
- Answer revealed: the 5 matching animals get green borders; the intruder gets a red ✕ overlay
- 10 semantic categories available (Mammals, Birds, Ocean Animals, Insects, Can Fly, Has a Shell, Lives in Water, Has Stripes, Big Animals, Small Animals)
11.13 Anagram - comming soon
Goal: Unscramble the letters to find the hidden word.
- A set of scrambled letter tiles is displayed alongside a category hint (Animals, Food, Sports, Nature, Objects)
- Three complete word options (A, B, C) are shown below
- Only one option is the word formed by the scrambled letters
- Players must select the correct word
- Answer revealed: correct option pulses green; wrong options fade
- Word pools are fully localised per language (English / Portuguese / Spanish), with difficulty tiers based on word length
11.14 Silhouette Build - comming soon
Goal: Identify which set of pieces can assemble the target silhouette.
- A large target silhouette is shown at the top of the card
- A 2×2 grid (A–D) shows four piece-set options; one correctly assembles the silhouette, three are distractors
- Players must select the correct letter
- Answer revealed: correct option cell gains a green border; incorrect options dim to 35% opacity
- Requires hand-authored puzzle assets; minimum 10 puzzles in the initial pool
12. Brain Star
When a player earns a brain star, a fullscreen celebration overlay appears:
- Player’s name and avatar
- Animated star
- “Amazing!” message
- Auto-dismisses after 2.5 seconds (or tap to skip)
13. Victory
Displayed when a player reaches 5 brain stars:
- Crown icon with the winner’s name and avatar
- “Congratulations” message
- Final standings table showing all players ranked by stars, then by correct answers
- Two action buttons:
- Play Again: Restart the game with the same players and challenge selection
- New Game: Return to the setup screen to start fresh