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# Tetrhex, version 1.02 (1995-03-13)

Note: this is the help text extracted from the rule Tetrhex. You need to read a part of TETRHEX help to understand everything.

## Presentation

Tetrhex is a kind of hexagonal tetris, that is played on a hexagonal board whose edge has 6, 7, 8 or 9 hexagons. The pieces are composed of 4 little hexagons of the same color (10 possible shapes up to a rotation, with equal probabilities). There are two kinds of pieces: normal pieces, and pieces whose hexagons have a bomb as a pattern, which appear with a probability equal to 1/10. The pieces appear at the top (in the center) and fall at a speed that depends only upon the level; you lose when the next piece can't appear.

The pieces can be moved

• in V (keys: left and right arrows), i.e. to the left or to the right at the same height; the height is by definition the number of the hexagons that are below;
• downwards to the left (8 o'clock) or to the right (4 o'clock); keys: Insert and Clr-Home;
• downwards (A on a QWERTY keyboard, Q on an AZERTY keyboard); in this case, the piece won't fall for the saved time.

The pieces can also be turned counterclockwise (down arrow) or clockwise (up arrow). A piece can be dropped with the space bar, to win points.

Hexagons can be destroyed in 3 different ways:

• By filling a line, i.e. a V (hexagons of the same height); there is an exception: the top hexagon does not form a line. All the hexagons of the line are destroyed.
• By making direct contact between loaded connected components. Two hexagons of the same color are in the same connected component if there exists a path linking these hexagons, which has only hexagons of this color. A connected component is loaded when one of its hexagons has a bomb as a pattern. direct contact means that the current piece has bombs, and after it stops, it must be in contact with a hexagon of another loaded connected component (the current piece forms a loaded connected component, with other possible hexagons of the same color). The hexagons of the loaded connected components are destroyed. Note: if lines are filled after this destruction, then these lines are destroyed.
• By exploding the whole board (Backspace key) if the current piece has bombs and if a bomb remains (remaining bombs).

The Help key allows to switch on and off the radar (the next piece is displayed). When the radar is switched on, 500 points are subtracted from the score (the score is set to 0 if it was less than 500). When the radar is on, the filled lines yield fewer points (see Section calculating the score).

The Undo key allows to pause. But the time goes on passing (see beneath). The Return key allows to continue.

Each level lasts 60 seconds. When the time (displayed at the bottom) reaches 0, the level is increased at the next piece (except for level 30). You can increase the level with the + key of the numeric pad; then the remaining time increases by 60 seconds. Thus, instead of spending one minute for each level starting at level 0, for instance you can select level 10, spend 11 minutes at level 10, then one minute at each following level.

To abort (whether the game is paused or not), type Ctrl-Esc.

## Calculating the Score

A piece that normally arrives (i.e. no drop) yields 3 points. A dropped piece yields max(3,D), where D is the difference in height + 1 between the drop and the arrival.

k filled lines yield f(k) × (L+10)², where L is the level, and f(k) is equal to: if the radar is off, f(1) = 2, f(2) = 5, f(3) = 10, f(4) = 20; if the radar is on, f(1) = 1, f(2) = 3, f(3) = 6, f(4) = 13.

The destruction by direct contact between loaded connected components yields [n(L+10)]² / 128, where n is the number of the destroyed hexagons.

The global explosion (with the Backspace key) yields 5 times the number of the destroyed hexagons (hexagons from the current piece included).

## Bomb Points

Bomb points are won in two different ways:

• by dropping a piece: this yields D/2 bomb points;
• by making direct contact between loaded connected components: this yields 8n bomb points.

When you reach a given number of bomb points, you get a bomb (remaining bombs). This number is 1000 if the edge of the hexagonal board has 9 cells, 800 if it has 8 cells, 600 if it has 7 cells, and 400 if it has 6 cells.

It may be interesting to join pieces of the same color so that more hexagons are destroyed by making direct contact between loaded connected components.

A (Q on an AZERTY keyboard), Insert and Clr-Home may be very useful to slide a piece under other pieces (to fill some holes).

The pieces with bombs are used in order to explode loaded connected components and to explode the whole board. It is better to delay the global explosion. You must sometimes take risks...

There are several stategies, sometimes conflicting. In some cases, you may try to have few hexagons on the board to maximize the drop points. You may try to fill several lines at the same time (4 if possible). You may try to make big connected components (the number of points is proportional to the square of the number of the destroyed hexagons).

## My Current Best Scores

• n = 9: 167,493
• n = 8: 125,112
• n = 7: 81,396
• n = 6: 17,685

Last updated:
• XML source: 2003-06-18, 23:39:56 (20)
• XSL stylesheet: 2003-08-06, 22:11:54 (488)
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