107 - Tromino Go

submitted by /dev/joe

Tromino Go

Credits:
Original game by Sid Sackson; published in the June 1994 issue of
Games magazine.  Adapted for e-mail play by /dev/joe.

Equipment: none

Players: exactly two players and one referee are required, no more, no
less.

Definitions:
A tromino, or "piece", is an L-shaped group of three like letters, such
as any of these examples:
AA  b    C
 A  bb  CC

A unit of edge is a length equal to the height or width of one letter
on any edge of a tromino.  Each tromino has four 1-unit edges and two 
2-unit edges.

Adjacent (or "touching"), in this game, means bordering on one or more
units of edge.  Trominoes which touch only diagonally are not considered
adjacent.

A group of trominoes is any single tromino, or any set of two or
more trominoes which belong to the same player such that a path can
be made from any one to any other tromino in the set by moving only
between adjacent trominoes.

A No Man's Land is any area of empty space completely surrounded by
trominoes.

Outside edge is any edge or portion of an edge of a tromino which does
not have another tromino or a No Man's Land adjacent to it.

A group of trominoes is surrounded if no tromino in the group has
any outside edge.
Beginning the game:
To begin an instance of Tromino Go, the referee should send a message
to the Gamesmaster listing the players; the Game and first round begins
when the Gamesmaster replies publicly to this and randomly chooses a
player to go first in the first round.

Rules:
1. General play rules
The player who loses each round starts the next round, if there is one;
if a round ends in a tie then the player who played second plays first
in the next round.  The player who plays first in a round always plays
using capital letters, and the other player uses lower case.  The plays
in each round always cycle through the letters A, B, and C, and the
players always alternate making plays, so the first six plays in a
round will always be A, b, C, a, B, and c, and then the sequence repeats.

2. The first four plays in a round
The first player begins by placing an A tromino in an otherwise empty
grid.  (Note that there is no limit to the grid; plays may always expand
in any direction, within the other restrictions of the rules.)

The second player then plays a b tromino so that it touches at least
two units of edge (which may be part of the same edge or different
edges) of the first tromino.  Some possible configurations after the
second play are:

AAb  AA   bbAA   AA
Abb  Abb   bA   bA
       b        bb

The first player then plays a C tromino so that it touches the b tromino
along at least two units of edge, but it does not touch the A tromino.

Then the second player plays an a tromino so that it touches at least
two units of edge of the C tromino, but does not touch the b tromino.

3. Plays Five to Thirty
After the first four plays in a round, until 30 trominoes have been
played,
each player in turn plays a tromino of the next letter in the sequence in
accorance with these three rules:
   i. It may not touch any other tromino of the same letter, regardless
      who played it (so an A tromino may not touch any other A or a
      trominoes, for instance).


 ii. It must touch at least one tromino played by the opponent along
      at least one unit of edge.
 iii. It must touch at least two units of edge of any trominoes already
      played (including the one unit required by rule ii).

4. Moving Trominoes
If 30 trominoes have been played without ending the round, then instead
of adding additional trominoes, each player moves one of his trominoes
of the appropriate letter to a new location.  Only trominoes with
some outside edge may be moved; a tromino which will split the grid
into two pieces if removed may not be moved.  The tromino's new position
must follow the rules in section 3 for playing new trominoes.  When a
round which has progressed to this phase ends, the player who wins
scores double the TGpoints he would normally score.

5. Handling a Stalemate
In any of the phases of play (rules 2 through 4 above), if a player
cannot make any other legal play, he may pass, leaving the grid unchanged
but advancing to the next letter in sequence and to the other player's
turn.  [This isn't commented on in the original rules, and I don't even
know if it's possible, but just in case, I've put this here.]

6. Winning a Round
A round ends when one or more groups of trominoes are surrounded.
At the end of a round, the player with the fewer surrounded trominoes
wins the round, and scores TGpoints equal to the number of his
opponent's surrounded trominoes minus the number of his own surrounded
trominoes.  If the two players have the same number of surrounded
trominoes then the round is a tie and nobody scores.

A player may cause his own trominoes to be surrounded by forming a
No Man's Land.  (A player may wish to do this intentionally to prevent his
opponent from surrounding a larger group of trominoes, or because it
simultaneously surrounds a group of his opponent's trominoes.)

7. Concessions
At any time either player may post a public message conceding the current
round of Tromino Go, along with a number of TGpoints they are conceding.
This does not end the round, and is not a play; the round continues
as usual until it ends normally, or a concession is accepted.

A player may accept any concession made by their opponent during the
current round of Tromino Go by stating so in a public message; if e
does so, the current round ends and e scores the indicated number of
TGpoints.

8. Winning the Game
When a player has scored 7 or more TGpoints in a game of Tromino Go,
e wins that game.  A player may also win the game if his opponent
fails to make a play within the 3 day time limit.  These are the only
ways to win the game.

When a player wins an instance of Tromino Go which was not played for
a Duel, an amount of A$ is transferred to that player from the treasury
as follows:  If e won by scoring 7 or more TGpoints, then e gets 2 times
the difference between his score in TGpoints and his opponent's score
in TGpoints.  Otherwise, e gets 14 minus twice eir opponent's score in
TGpoints.  In addition, at the end of any instance of Tromino Go, the
referee gets A$1 from the treasury for each round completed, to a
maximum of A$10.

9. How Plays are Made
Players should play by reposting the previous grid, with their new
play added/moved as appropriate, in a public message.  Players need
not wait for the referee to comment on a play before making the next
play; the referee should watch for illegal plays, but need not make
any comment unless an illegal play is discovered, or a play has been
questioned, or a round has ended.

Each player has 3 days from the time of the previous play (or from the
beginning of the round, for the case of the first play) to make a play
when it is his turn, or else e loses the game.

10. Handling Illegal Plays and the End of a Round
If a player believes an illegal play has been made, he may post so
publicly, and the referee should post publicly either that all
plays are legal, or indicate the first illegal play which has been
made.
  - If all plays are legal, then play continues where it left off; no time
    between the the public request to verify the plays and the referee's
    response counts toward the 3 days a player has to make a play.
  - If the referee determines that an illegal play has been made, then
    that play and all plays since that are ignored, and play continues
    with the player who made the illegal play making a new play.  No time
    between the initial post of the illegal play and the referee's post
    indicating the illegal play shall count against the 3 days the player
    has to make a play.

If the referee finds that an illegal play has been made, he may post
so publicly without any request to do so, and the same corrections as
in the preceding section shall be applied.

If the referee posts that a round has ended, e should include with this
message the winner of the round, the TGpoints scored, and the total
TGpoints each player has.  If this does not end the game, the next
round begins at the time of this post.  If it does end the game, the
referee should post the final score, who won, and the A$ transfers
resulting from it.

11. Substitutions
A player may appoint another willing player not already involved with the
game to play in his place for any time that e is on vacation.  If a player
leaves the game of Ackanomic, e loses the game of Tromino Go.

The referee may appoint another willing player not already involved in the
game to play in his place for any time that e is on vacation or is no
longer a player in Ackanomic.  If the referee goes on vacation or leaves
Ackanomic without making such an appointment, the Gamesmaster may
appoint a referee.