Drop7 is a one-player puzzle on a 7 by 7 grid. Each turn you are handed a numbered disc
to drop in an available column. The disc falls, can explode based on rules described below,
and can set off a chain reaction of explosions as falling discs rearrange themselves. Every
five turns, the whole board is pushed up one row by a fresh row of gray "hidden discs".
Creating explosions near the hidden discs cracks and reveals a number. Keep the board from
overflowing for as long as you can, and score as much as you can on the way.
The rest of this page makes that short description more precise.
1. The board and the pieces
There are only three kinds of thing on the board, plus empty space:
numbered disc (1–7)
clears when its row-run or column-run is exactly its number
solid gray disc
hides a number; counts as occupied; needs two hits to open
cracked gray disc
has taken one hit; one more reveals the number underneath
empty cell
discs fall through it; a run stops at it
This is what the player sees when playing the game.
The visible board, the next disc, and the rise clock are public. What is under a gray disc is unknowable until it is opened, and nobody knows which discs are coming after the next one.
2. A turn: pick a column
You do not place the disc in a cell; you choose one of the seven columns and
gravity does the rest.
1. Before the move
2. The disc drops to the lowest empty cell
3. Settled — ready for the next disc
Result: score +0
The simplest possible move: the disc lands and nothing matches.
A column is legal only while its top cell is empty. A full column cannot take a
disc, and it matters for the rise too (section 7):
3. The one rule: a disc clears when its run equals its number
A numbered disc disappears when the unbroken line of occupied cells through it —
counted along its row, or along its column — has a length exactly equal
to its number. Count the run, compare it to the disc, done.
Three occupied cells in a row through this 3. The run is exactly 3, so it clears — and so do the other two 3s in the run, because their own runs are also 3.
1. Before the move
2. The disc drops to the lowest empty cell
3. Wave 1: 3 discs match and clear (+21)
4. Cleared
5. Settled — ready for the next disc
Result: score +21 · 1 wave (wave 1: 3 × 7)
A horizontal clear. The wave clears every matching disc at once — it is never one disc at a time.
The same rule reads downwards. A column-run counts the occupied cells stacked
directly above and below the disc:
1. Before the move
2. The disc drops to the lowest empty cell
3. Wave 1: 3 discs match and clear (+21)
4. Cleared
5. Settled — ready for the next disc
Result: score +21 · 1 wave (wave 1: 3 × 7)
A vertical clear. A disc only needs one of its two runs to match.
The match has to be exact. A run that is too long does nothing:
This 2 sits in a run of three. 3 is not 2, so it stays. A disc is never cleared for being in a run longer than its number.
1. Before the move
2. The disc drops to the lowest empty cell
3. Settled — ready for the next disc
Result: score +0
Too long is as good as too short. Overbuilding a run is one of the classic ways to lock numbers onto the board.Three 3s and a gray disc form a run of four. The gray disc lengthens the run, so the 3s do not clear.
1. Before the move
2. The disc drops to the lowest empty cell
3. Settled — ready for the next disc
Result: score +0
The same three 3s that cleared in section 3 — blocked by one gray disc counting as a fourth cell.
4. Gray discs: cracking and revealing
A solid gray disc hides a number from 1 to 7. It opens in two
steps. Whenever a disc directly next to it (above, below, left, or right —
never diagonally) clears, the gray disc takes one hit:
the first hit turns a solid disc into a cracked disc ;
the second hit reveals the number underneath, which becomes an ordinary
numbered disc from then on.
Hits are counted per wave, on the board as it was just before the wave's discs
were removed. A cracked disc therefore needs one more hit; a solid disc hit by
two clearing neighbours in the same wave opens immediately.
1. Before the move
2. The disc drops to the lowest empty cell
3. Wave 1: 3 discs match and clear (+21)
4. Cleared — and neighbouring gray discs take hits
5. Gravity: everything above falls
6. Settled — ready for the next disc
Result: score +21 · 1 wave (wave 1: 3 × 7)
One hit cracks. The disc is still an obstacle, still counts toward runs, and still hides its number.
1. Before the move
2. The disc drops to the lowest empty cell
3. Wave 1: 3 discs match and clear (+21)
4. Cleared — and neighbouring gray discs take hits
5. Gravity: everything above falls
6. Settled — ready for the next disc
Result: score +21 · 1 wave (wave 1: 3 × 7)
Two hits open a gray disc. Revealing is how the board gets new numbers — and how it gets new problems.
Those two hits do not have to come on different turns. Place a 3 on each side of a solid gray disc and both numbered discs sit in a row-run of three — so they both clear, and the gray disc is hit from left and right at once:
1. Before the move
2. The disc drops to the lowest empty cell
3. Wave 1: 2 discs match and clear (+14)
4. Cleared — and neighbouring gray discs take hits
5. Settled — ready for the next disc
Result: score +14 · 1 wave (wave 1: 2 × 7)
Two neighbours clearing in the same wave skip the cracked state. The gray disc never exists as a cracked disc on this board.
The same counting works when the two hits are not on opposite sides:
1. Before the move
2. The disc drops to the lowest empty cell
3. Wave 1: 4 discs match and clear (+28)
4. Cleared — and neighbouring gray discs take hits
5. Settled — ready for the next disc
Result: score +28 · 1 wave (wave 1: 4 × 7)
Two hits in the same wave open a solid disc at once. Hits are judged on the board before the clear, so a disc that is about to be removed still counts as a neighbour.
A gray disc hides one number from 1 to 7, drawn uniformly. Nothing you do
changes the odds — you only control when and whether it is exposed.
5. Gravity and chain reactions
When discs clear, everything above them falls straight down. If the fall
creates a new match, those discs clear too — that is wave 2, and it can go
on. Each wave is worth more than the last (section 6).
1. Before the move
2. The disc drops to the lowest empty cell
3. Wave 1: 3 discs match and clear (+21)
4. Cleared — and neighbouring gray discs take hits
5. Gravity: everything above falls
6. Wave 2: 1 disc match and clear (+39)
7. Cleared — and neighbouring gray discs take hits
A two-wave chain. Notice that the second wave was caused by a disc that did not exist before the move — the revealed 1 — which is why reveals are the engine of long chains.
Everything inside one move — however many waves — happens before the next disc
is offered, and the player has no decisions to make during it.
6. Scoring
Each disc cleared in chain wave d is worth floor(7 × d^2.5) points. The
curve is steep on purpose: a disc in wave 8 is worth 181 times a disc in wave 1.
Points per cleared disc, by chain wave — floor(7 × d^2.5)
table view
chain wave
points per disc
1
7
2
39
3
109
4
224
5
391
6
617
7
907
8
1,267
Per-disc value by wave. Multiply by the number of discs in the wave; a wave of three discs at depth 3 is 3 × 109 = 327.
Two bonuses sit on top of the wave points:
Event
Bonus
When
the board rises (every fifth drop)
17,000
awarded with every rise, on top of whatever the move scored
the board is completely empty after a move
70,000
awarded whenever a move ends with no discs on the board at all
Clearing the last discs. The 70,000 is awarded at the end of the move, after every wave has resolved.
7. Every fifth drop, the board rises
A clock counts down from 5. Each drop ticks it once. When it reaches zero, the
whole board shifts up one row and a new row of seven solid gray discs
appears along the bottom. The clock resets to 5 and play continues.
1. Before the move
2. The disc drops to the lowest empty cell
3. Fifth drop: the board rises (+17,000)
4. Settled — ready for the next disc
Result: score +17,000 · the board rose and the rise clock reset to 5
The rise happens after the move's own cascade has finished. If the new row creates matches, those clear as a continuation of the same move — the wave counter does not restart.
Two details of the rise matter for strategy. It happens after the cascade
of the move that triggered it, not before; and the seven new gray discs are
seven more unknown numbers and seven more occupied cells, which lengthens
every vertical run passing through them.
8. How a game ends
There are exactly two ways for a game to end, and both are about running out of
room:
The board cannot rise. When the clock reaches zero, every column must
have an empty top cell for the board to shift up. If any column is stacked
to the top, the rise is impossible and the game is over.
No column can take a disc. If every column is full, there is no legal
move, and the game is over.
1. Before the move
2. The disc drops to the lowest empty cell
3. Game over
Result: score +0 · the game is over
A blocked rise. A single full column ends the game even when six other columns have plenty of space — which is why height is the thing every strategy here watches most closely.
Nothing else ends a game: there is no timer, no move limit in the rules
themselves (the research benchmarks cap games at 2,000 moves and mark those as
censored), and no way to lose points.
9. The whole rulebook in one table
Rule
Precisely
Board
7 columns × 7 rows.
A turn
You are shown the next disc; you choose a column whose top cell is empty; the disc falls to the lowest empty cell in that column.
Clearing
A numbered disc clears when the contiguous run of occupied cells through it, along its row or its column, has length exactly equal to its number. Gray discs count as occupied.
Waves
All matching discs clear simultaneously; gravity then pulls everything above them down; if new matches exist, the next wave clears them; repeat until nothing matches.
Gray discs
A hit is an orthogonally adjacent disc clearing in the current wave, judged on the pre-clear board. Solid + 1 hit = cracked. Cracked + 1 hit = revealed. Solid + 2 hits in one wave = revealed. The revealed number is uniform on 1–7; this engine draws it at reveal time unless latent mode fixes it in advance (see section 4).
Wave score
floor(7 × d^2.5) points per disc cleared in wave d: 7, 39, 109, 224, 391, 617, 907, 1,267, …
Rise
After every fifth drop (and after that move's cascade), the board moves up one row and a row of seven solid gray discs appears at the bottom; +17,000. A cascade caused by the new row continues the move's wave count.
Board clear
A move that ends with an empty board earns +70,000.
Game over
The board must rise but some column's top cell is occupied; or no column can accept a disc.
Information
The player — and any legal policy — sees only the board, the next disc, and the rise clock. Hidden gray values and future discs are unknown.
Why the strategy is hard
A move is never just its immediate clear. It changes which gray discs get hit,
which numbers fall together, how tall each column is when the next rise comes,
and which hidden numbers will surface later. Good play keeps numbers flowing —
clearing and revealing steadily — so that the board never stacks up, while
building the shapes that turn a single drop into a deep, high-scoring chain.