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

Tet'light is a kind of hexagonal tetris, that is played on a hexagonal board whose edge has 6, 7, 8 or 9 hexagons. This is an easier version than Tetrhex, for people who find Tetrhex too difficult. The pieces are composed of 4 little hexagons of the same color (10 possible shapes up to 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, which is a set of hexagons being in different and
successive columns, such that the hexagons are aligned and the alignment
is maximal, i.e. each cell aligned with these hexagons isn't
empty, or such that the hexagons form a maximal V (non necessarily
symmetrical), i.e. there is a column
`c`such that one has two maximal alignments to the left and to the right of`c`, and pointing upwards. Equivalent formulation: if the board is extended to a paving of the whole plane with hexagonal cells, then the lines are the (non-empty) intersections of the infinite V's with the initial board (a V is formed by two half-lines having the same origin, the one pointing upwards to the left (10 o'clock) and the other pointing upwards to the right (2 o'clock)). Exception: the cell situated at the top of the board in the center is always considered empty. Lines may be destroyed in several steps, i.e. if after a destruction one or several lines are formed, then these lines are destroyed. - If the current piece has bombs: at the first step, by making contact between loaded connected components of different colors, one of which has the current piece. Then the hexagons of these connected components are destroyed. 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.
- 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,
100(`L`+5) points are subtracted from the score, where
`L` is the current level (the score is set to 0 if it becomes
negative). When the radar is on, the filled lines yield twice as many
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 40 seconds. When the time (displayed at the bottom)
reaches 0, the level is increased at the next piece (except for level 35).
You can increase the level with the `+` key of the numeric pad;
then the remaining time increases by 40 seconds. Thus, instead of spending
40 seconds for each level starting at level 0, for instance you can
select level 5, spend 4 minutes at level 5, then 40 seconds at each
following level.

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

Note: in GEM window mode, when the window is in the background, the time doesn't decrease any longer, but the time passing continues as soon as the window is topped.

A piece that normally arrives (i.e. no drop) yields 5
points. A dropped piece yields max(5,2`D`), where `D`
is the difference in height + 1 between the drop and the arrival.

The hexagon destruction by filling lines or by making contact between
loaded connected components yield
(1+`r`) × (`L`+10) points for each destroyed
hexagon, where `r` = 1 if the radar is on,
`r` = 2 if it is off, and `L` is the level.

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

*Bomb points* are won in two different ways:

- by dropping a piece: this yields
`D`bomb points if`D`≥ 3; - by making contact between loaded connected components: this
yields 10
`n`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 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 both explode loaded connected components and explode the whole board. It is better to delay the global explosion. You must sometimes take risks...

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