.\"	$NetBSD: tetris.6,v 1.18 2023/07/01 10:51:35 nia Exp $
.\"
.\" Copyright (c) 1992, 1993
.\"	The Regents of the University of California.  All rights reserved.
.\"
.\" This code is derived from software contributed to Berkeley by
.\" Nancy L. Tinkham and Darren F. Provine.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\"    notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\"    notice, this list of conditions and the following disclaimer in the
.\"    documentation and/or other materials provided with the distribution.
.\" 3. Neither the name of the University nor the names of its contributors
.\"    may be used to endorse or promote products derived from this software
.\"    without specific prior written permission.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
.\" SUCH DAMAGE.
.\"
.\"	@(#)tetris.6	8.1 (Berkeley) 5/31/93
.\"
.Dd July 1, 2023
.Dt TETRIS 6
.Os
.Sh NAME
.Nm tetris
.Nd the game of tetris
.Sh SYNOPSIS
.Nm
.Op Fl bps
.Op Fl k Ar keys
.Op Fl l Ar level
.Sh DESCRIPTION
The
.Nm
command is a display-based game.
The object is to fit the shapes together forming complete rows,
which then vanish.
When the shapes fill up to the top, the game ends.
You can optionally select a level of play, or custom-select control keys.
.Pp
The default level of play is 2.
.Pp
The default control keys are as follows:
.Pp
.Bl -tag -width "xxspacexx" -compact -offset indent
.It j
move left
.It k
rotate 1/4 turn counterclockwise
.It l
move right
.It Aq space
drop
.It p
pause
.It q
quit
.It n
down
.El
.Pp
The options are as follows:
.Bl -tag -width indent
.It Fl b
By default, shapes are displayed colorfully if the user's CRT supports color.
The
.Fl b
option can be used to restore the traditional black-and-white behavior.
.It Fl k
The default control keys can be changed using the
.Fl k
option.
The
.Ar keys
argument must have the seven keys in order, and, remember to quote any
space or tab characters from the shell.
For example:
.Pp
.Dl "tetris -l 2 -k 'jkl pqn'"
.Pp
will play the default games, i.e. level 2 and with the default
control keys.
The current key settings are displayed at the bottom of the screen
during play.
.It Fl l
Select a level of play.
.It Fl s
Display the top scores.
.It Fl p
Switch on previewing of the shape that will appear next.
.El
.Sh PLAY
At the start of the game, a shape will appear at the top of the screen,
falling one square at a time.
The speed at which it falls is determined directly by the level:
if you select level 2, the blocks will fall twice per second;
at level 9, they fall 9 times per second.
(As the game goes on, things speed up,
no matter what your initial selection.)
When this shape
.Dq touches down
on the bottom of the field, another will appear at the top.
.Pp
You can move shapes to the left or right, rotate them counterclockwise,
or drop them to the bottom by pressing the appropriate keys.
As you fit them together, completed horizontal rows vanish,
and any blocks above fall down to fill in.
When the blocks stack up to the top of the screen, the game is over.
.Sh SCORING
You get one point for every block you fit into the stack,
and one point for every space a block falls when you hit the drop key.
(Dropping the blocks is therefore a good way to increase your score.)
Your total score is the product of the level of play
and your accumulated
.ie t points\(em200
.el points -- 200
points on level 3 gives you a score of 600.
Each player gets at most one entry on any level,
for a total of nine scores in the high scores file.
Players who no longer have accounts are limited to one score.
Also, scores over 5 years old are expired.
The exception to these conditions is that the highest score on a given
level is
.Em always
kept,
so that following generations can pay homage to those who have
wasted serious amounts of time.
.Pp
The score list is produced at the end of the game.
The printout includes each player's overall ranking,
name, score, and how many points were scored on what level.
Scores which are the highest on a given level
are marked with asterisks
.Dq * .
.Sh ENVIRONMENT
.Nm
honors the informal standard
.Dv NO_COLOR .
When it is set in the environment, no color will be used.
.Sh FILES
.Bl -tag -width /var/games/tetris.scoresxx
.It /var/games/tetris.scores
high score file
.El
.Sh AUTHORS
.An -nosplit
Adapted from a 1989 International Obfuscated C Code Contest winner by
.An Chris Torek
and
.An Darren F. Provine .
.Pp
Manual adapted from the original entry written by
.An Nancy L. Tinkham
and
.An Darren F. Provine .
.Pp
Code for previewing next shape added by
.An Hubert Feyrer
in 1999.
.Sh BUGS
The higher levels are unplayable without a fast terminal connection.