TETRI differs from Windows-like versions of
Tetris in that the player fights with growing complexity, not
with growing speed. The result depends largely on the
player's skill and to a lesser extent on a lucky chance. What
makes the game fascinating is the difficulty caused by the
random dice distribution in the first n lines. A good player
survives as a rule level 7, a very skilled player even level
9 or 10. The same game can be repeated several times with
option Same, with precisely the same random dice
distribution when starting in the same level. Thus, one can
successively improve a first approach or compete with other
players starting with the same dice distribution.
You may load a library (TETRI.lib) or a directory
(TETRI.dir). Advantage of the library is that you get its
menu directly from the category GAMES on the APPS key. The
directory is 200 bytes smaller. If a separate High score
storage is needed for your partner playing on the same
calculator, load both. The library and the directory have
different High Score storage places. TETRI uses the PICTURE
environment. Hence, save your own grob in PICTURE if
necessary. Both versions are tested in ROM 1.19-6 on the 49G
and ROM 2.05-4 on the 49g+.
---------------------------------------------------------------------------
NEW in version 3.2006
Version with "PICT-reset". Older versions do not
work properly when PICT is oversized in width. TETRI is now
first clearing the graph display.
NEW in version 2.2006
Adapted to ROM > 1.24.
NEW in version 2.2003
Level choose box now independent on real number display.
NEW in version 1.2003
Turn-off suspension improved. When turning on, the 49G/49g+
keeps waiting on a first
key. In the library, |Seed| toggles store/recall. |MUTE|
replaced by |SND?|.
NEW in version 6.2002
The TETRI command sets the menu |NEW| |Pict| |->Seed|
|Mute| |Top| |Same|.
Mute/sound-switching also with +/- during the game.
NEW in version 1.2002
A command |Same| has been added to repeat a lost game.
----------------------------------------------------------------------------
TETRI has a 1-page menu as follows: New
Pict Seed Snd?
Top Same?
New starts a new game. Pict shows last graphic
after a finished game. In the TETRI library, Seed toggles
recalling/storing your favourite real as a seed for the
random sequence used if started with Same. In the
TETRI directory, Seed is an ordinary global in which you may
store any real as usual. Top always shows the highest
score. Snd? toggles sound/silent mode which can be
toggled also during the game but is valid only till the game
is over. Clearly, Same repeats the last game only if starting
in the same level. Then you get the same dice distribution
and the same dropping sequence.
New or Same provide a choice of 10 start levels. To choose a
level one may use a numeric key or the arrow keys. For
instance, a start in Level 10 is realized by just tipping on
the UParrow key. You run into the next level if the current
one is successfully completed, i.e., if the number of lines
displayed beneath LINES has been erased. Besides the arrow
keys for moving the dropping figures and CANCEL for aborting,
the following keys are active *during* a game. These are all
somehow symbolized on the screen to remind on their
existence.
NXT interrupts the game to get time for deciding where
to locate the figure, depending on the next piece shown to
the left of the play box. Pressing NXT twice turns the
49G/49g+ off. The game will be resumed at the next turn-on.
The +/- key toggles sound/silent mode for the current
game only. Pressing the + key once or several times increases
dropping speed. - decreases the dropping speed. The last
speed will always be saved in memory. Thus, dropping speed is
readily adapted to your convenience. Do not too hasty move a
figure to the left or right in the very upper part of the box
- it may jump over the margin as shown in the left-hand
sceen-shot and the game is lost . A new High score is
visually and acoustically announced, see the right-hand
screen. It is hidden and manipulation is normally impossible.
Score rules for TETRI are simple. The higher
the level, the higher the score after successfully
completing a level. A bonus is added at the end, depending on
the number c of clean lines at the moment of completion; the
more lines are
clean the higher the bonus. It is maximal for c = 14, i.e.,
all dice have been removed in the very moment of completion.
Exact score calculation below. When level n is lost, the game
will be over. The last bonus is either 0 or n^2.
Exact Score computation in Level n. Each dropping adds n points to the score, each erased line 2n additional points. Precisely 2n+16 lines have to be erased. When successfully completing level n, a bonus of c(n+1)^2 points is added to the score where c is defined above. Hence, a completed level n contributes at least (n+1)^2+n^2+2n(n+16)+2n(2n+16) points to the score.
Remark. There is a serious bug in ROM
1.22. Press NXT very short, Otherwise you may ran into
difficulties if trying to resume the game after a turn-off
with NXT.
Credits. Thanks to Daniel
Lidström for porting TETRI from the 48 to the 49G/49g+ and
for giving support.
Wolfgang Rautenberg,
2006-02-15
raut@math.fu-berlin.de
www.math.fu-berlin.de/usr/raut