Molecular Scrabble Manual

01The two editions

Molecular Scrabble is a crossword tile game in which you spell chemical formulas instead of words, laying element tiles on a 15×15 board. There are two digital editions. Both use the same board, tiles and scoring.

Throughout this manual, a Full Edition label marks anything that only the Full Edition does. Everything else applies to both.

02Quick start

1. Open either edition and choose the Play tab.
2. Pick a mode: Solitaire on your own, Pass and Play to share one screen, or an Online Table Full Edition.
3. Decide whether to tick Theory Mode. With it on, any molecule you could draw counts, even one nobody has made. New players and anyone without a Claude account should leave it on.
4. Tap a tile in your rack, then tap a square on the board. Repeat to spell a formula across or down. Your first formula must cover the centre star ✦.
5. Tap Submit formula. If every formula you made is valid, you score and your rack refills to 7 tiles.

03The tiles

The bag holds 116 tiles: 112 element tiles in 33 elements, plus 4 blank Wild Isotope tiles. Common light elements are plentiful and cheap. Rare and heavy elements appear once or twice and are worth more. The small number on each tile is its points value; the figure beneath shows how many are in the bag.

Wild Isotope tiles

A Wild Isotope stands in for any element and scores 0. Tap it in your rack and a row of element buttons appears below the rack. Choose the element it should be, then tap a square. The board shows the chosen symbol with a value of 0.

Each player holds 7 tiles. The game shows how many tiles are left in the bag above the board.

04The board

The board is 15×15 with the standard Scrabble pattern of premium squares. A premium counts only on the turn a tile is first placed on it. Tiles already on the board score their plain value.

05Playing a turn

On your turn, do one of three things.

Play a formula

• Tap a rack tile to lift it, then tap an empty square. To take a tile back, tap it on the board, or tap Recall tiles to return them all.
• All the tiles you place go in one row or one column, with no gaps. Tiles already on the board can fill the line between yours.
• The very first formula of the game must cover the centre star and use at least two tiles.
• After that, every play must touch tiles already on the board. A single tile is allowed when it extends or crosses an existing formula.
• Tap Submit formula. The main formula and every crossing formula you made are checked. If any is rejected, a red message explains which one; rearrange or recall your tiles and try again. A rejected attempt doesn't use up your turn.

Exchange tiles

Tap Exchange tiles, tap the rack tiles you want to swap, then Confirm exchange. They go back in the bag and you draw the same number. You can't swap more tiles than the bag holds. In Pass and Play and Online Tables, exchanging uses your turn. In Solitaire you have three exchanges per game.

Pass

Tap Pass to give up your turn. Solitaire has no Pass button; you end the game instead.

06What counts as a formula

This section describes Standard Mode, the default in the Full Edition. Theory Mode is more generous and has its own section.

• A formula must be a real, recognised substance: a compound or an element's usual molecular form, such as O₂.
• It must be charge-balanced and stoichiometrically sensible.
• Elements go in the conventional order chemists write them. NaCl is valid; ClNa is not.
• Subscripts are made by repeating tiles: H₂O is played as H · H · O.
• Formulas read left to right or top to bottom, like words.

07Scoring

1. For each formula you made this turn, add up its tiles' points.
2. Apply letter premiums (DL, TL) to newly placed tiles first.
3. Then multiply by any word premiums (DW, TW) under newly placed tiles. Two word premiums in one formula multiply together.
4. Every crossing formula scores in full as well as the main one.
5. Using all 7 rack tiles in one turn adds a +15 Full Reaction bonus.

Worked example: the opening play

Water played across the centre, with the middle hydrogen on the star (a Double Word square):

The game adds up your score for you and records each play in the Lab notebook beside the board.

08Ending the game

In Pass and Play and Online Tables, the game ends in one of two ways.

• Someone goes out. The bag is empty and a player places their last tile. Every other player loses the points value of the tiles left on their rack, and the player who went out gains the total of those leftovers.
• Everyone is stuck. Every player passes twice in a row. Each player then loses the value of their own leftover tiles. An exchange breaks the run of passes. At an Online Table, a turn skipped because the timer ran out counts as a pass.

The highest final score wins, and equal top scores are a tie. Solitaire ends differently; see Solitaire.

09Solitaire 1 player

Play alone against the bag and score as much as you can from one bag of tiles. The board, formula rules and scoring are the same as the main game. There are no opponents and no turn timer.

• Start from the Practise at your own bench panel on the Play tab. Tick Theory Mode first if you want it.
• You get three exchanges per game, while the bag still has tiles.
• There are no passes. When you're stuck and out of exchanges, tap End game and confirm.
• Use every tile in the bag and on your rack for a +25 Clean Bench bonus. The game ends by itself when you place your last tile.
• If you end early, the value of the tiles left on your rack is subtracted.

The side panel shows your score, your rank, how far you are from the next rank, formulas played, exchanges left and your best single play. In Theory Mode it also counts the hypothetical molecules you've invented.

Standard Mode and Theory Mode keep separate personal bests, since Theory Mode accepts more formulas.

10Pass and Play 2–4 players, one device

Share one phone, tablet or computer and take turns.

1. On the Play tab, type in two to four names. Leave players 3 and 4 blank to skip them.
2. Tick Theory Mode if you want it, then tap Start pass and play. The game draws at random who goes first.
3. The screen says Pass the device to the next player and shows the last move. Nobody's tiles are visible.
4. That player taps I'm … — show my tiles and takes their turn. When the turn ends, the tiles disappear again.

The board, scoreboard and how many tiles each player holds stay visible throughout. Exchanges and passes are unlimited; each uses your turn. At the end, the results screen shows the winner, how the game ended and each player's leftover adjustment. Rematch starts again with the same players.

11Online Tables Full Edition

Each player uses their own device, wherever they are.

Opening a table

1. On the Play tab, under Open a private table, enter your name, choose 2, 3 or 4 players and tick Theory Mode if you want it. The host's choice applies to everyone.
2. Tap Open table. You're taken to the waiting room, which shows the table's link and its six-character code.
3. Send friends the link (Copy link helps), or give them the code to type under Join with a code.
4. When at least two players have joined, the host taps Start match.

During the match

• Each turn has a 3-minute timer. If it runs out, that turn is skipped.
• You see only your own rack. The scoreboard highlights whose turn it is.
• The Lab notebook logs every play, with the AI chemist's summary and a chemistry fact.
• If you close the page, open the table link again on the same device and browser to return to your seat.

12Theory Mode

Theory Mode lets you invent molecules nobody has made yet. It's available in Solitaire, Pass and Play and Online Tables.

The rules

• A formula is valid if its atoms could be joined into one neutral, connected structure in which every atom's valency is satisfied. In other words, you could draw it on paper.
• A real substance is always valid, even where the simple valency rules don't fit it. Carbon monoxide (CO) is one example.
• Tile order doesn't matter: ClNa is as good as NaCl.
• Still rejected: formulas with atoms left needing bonds, charged ions, anything with helium or neon, and separate molecules side by side. Formulas still need at least two tiles.

The usual valencies used for each element:

Known and hypothetical

Each accepted formula is marked in the Lab notebook as known, or tagged Hypothetical if it isn't a documented substance. In the Full Edition the AI chemist also names your molecule and sketches one way its atoms could bond, for example O=C=C=O.

Without the AI, only formulas on the built-in list count as known. Other real compounds, glucose for instance, are still accepted but tagged Hypothetical.

13Who checks the formulas

There are three referees. The game picks one automatically.

The AI chemist is a quick model making a judgement call. It's good on everyday chemistry but can occasionally be wrong about obscure compounds, in either direction.

14Saved games and personal bests

• Solitaire: tap Save and leave bench, or simply close the page. The Play tab then offers Resume game.
• Pass and Play: tap Save and leave game. A resumed game always opens on the hand-off screen, so nobody's tiles show by accident.
• Online Tables Full Edition: the table itself is kept online. Reopen its link on the same device and browser to rejoin.

Saved games and personal bests live in the browser on that device. They don't move to another device or browser, and they're lost if you clear the browser's site data or play in a private window.

15Accounts and sharing

Public Edition

Anyone with a web browser can play. It needs no sign-in and makes no connection to Claude. When the game is updated, the website copy must be replaced with the new file.

Full Edition

• The page is hosted on Claude. Its owner can share it from the page's Share menu.
• Visitors without a Claude account can still use Solitaire and Pass and Play, with the built-in referees.
• The AI chemist needs the player's own Claude account.
• Online Tables need players signed in to Claude in the owner's organisation, with edit access.
• People opening a shared link may see an earlier version until the owner updates the shared version from the Share menu.

16Problems and questions

My formula is a real compound, but it was rejected.

Without the AI chemist, Standard Mode knows only 42 formulas, and only in the exact tile order on the reference card. Check the order, or switch on Theory Mode.

A tile won't go onto the board.

Tap a rack tile first, then the square. For a Wild Isotope, choose its element from the buttons below the rack. If Exchange is active, finish or cancel it first.

The game says my tiles must connect or be in one line.

All tiles placed in one turn go in a single row or column with no gaps, and they must touch something already on the board. The first play must cover the centre star.

I can't exchange.

The bag may be empty, you may have picked more tiles than it holds, or in Solitaire you may have used all three exchanges.

My friend can't join my Online Table.

They need to be signed in to Claude in the same organisation as the game's owner, with edit access. Otherwise, play Pass and Play together on one device.

My saved game or personal best has gone.

Saves are kept in the browser on the device you played on. A different device, a different browser, a private window or clearing site data starts fresh.

The AI chemist isn't checking my formulas.

You may not be signed in to Claude, may have declined its permission request, or may be using the Public Edition. The game falls back to the built-in rules and says so in the Lab notebook.

17Reference card

The built-in list used when the AI chemist isn't available. Every formula here counts as known in Theory Mode.

18Table variants for the boxed set

These optional rules come from the physical game. They aren't built into the digital editions, but you can agree to play them by hand at the table.

• Biology Bonus: +5 points for any formula found naturally in the human body, such as H₂O, CO₂, NaCl or C₆H₁₂O₆.
• Organic Chemistry Mode: only carbon-chain formulas count.
• Ion Rules: charged species are allowed, written with superscripts.
• Teach and Challenge: instead of a straight challenge, the player explains their formula.
• Speed Lab: a 60-second turn timer.
• Junior Chemist: the reference card may be used at the table.