Sigma 4 Shogi

Sigma 4 Shogi is a highly tactical variant containing some parts of the Shogi rule set. There are no pawns in this game.
In this game you can "promote" your pieces aka. bases by taking the opponents bases. But there is a limit on how far you can upgrade the bases.

Sigma is the greek sign for "Sum". The number 4 counts for the number of stones can be on a base. This means you can sum up to four stones on one base.(Two if it is the royal base)

Setup

The Board is a 7x7 one with alternate black/white colored squares.
An exception to this are the corners. They are bright red on the white side and dark red on blacks side. The squares d1 and d7 in which the royal bases are starting, are containing a circle each. Additionally each player have an area called "Storage" which is outside of the board.

White places his bases on the rightangle a1-g3 with the royal base being on d1. Black makes the same in a5 to g7 and places his royal base on d7.
The row 4 stays empty.

The target is to either checkmate or to stalemate the opponent or to reach the opponents circled square with own royal base.

Pieces

Each player have 21 pieces. Each piece is build with a base and up to four stones. There can never be a base in the game with no stone into it.
The stones gives its base the movement abilities.
Therefore each player have 21 bases in his color. 20 are normal bases with room for four stones and one is a royal base, which have room only for two stones. The royal base is labeled R in the notation while the other bases are not labeled.

There are 8 base stones:
Base stones
Wazir (W) steps 1 square ortagonally.
Ferz (F) steps 1 square diagonally.
Dabbaba (D) jumps 2 squares ortagonally, can jump intervening pieces.
Elephant (E) jumps 2 squares diagonally, can jump intervening pieces. 
Knight (N) moves like the chess knight
Jumper (J) jumps 3 squares ortagonally or diagonally, can jump intervening pieces.
Zebra (Z) is a sort of 3/2 knight if assumed the standard chess knight is a 2/1 knight. Can as well jump intervening pieces.
Camel (C) is a 3/1 color bounded knight type piece. Can jump intervening pieces.


Each player have a set of 42 stones:
They are categorized in ranks.

Rank 1 can be placed up to four of these on a base making it extending the moves. That means adding 4 W on a base makes is moving like a short range rook.

8 Wazir (W)
8 Ferz (F)

Rank 2 can be placed up to four times (twice per type) per base. Can extend the moves once if twice of the same type is on the same base. Totally only 2 per type on any base. That means you can add 2 E and 2 D but not 3 E or 3 D.

8 Dabbaba (D)
8 Elephants (E)

Rank 3 can only be placed once per base. That means per base there can only exists one rank 3 stone at all. This is done because rank 3 stones allows to reach double amount of quares be reached in opposite to rank 1 and 2 stones.

2 Zebra (Z) 
2 Camel (C)

Rank 4 can exist only once per base also. That means per base there can only exist one rank 4 stone at all. This is done because rank 4 stones allows to reach double amount of quares be reached in opposite to rank 1 and 2. Furthermore can rank 4 pieces not be added to the royal base at all.

4 Knights (N)
2 Jumpers (J)

At the beginning of the game only one rank 3 or rank 4 stone can exists per base. See rule A4

Rules

A) Setting up the stones in the bases:
Each player distributes his stones at will on his 21 bases with some limitations:
1) Jumpers (J), Camels (C) and Zebras (Z) can not be placed on the bases in the corners or on the royal pieces at the beginning. The knight can not be placed on the royal base at all but it can be placed in the corner bases.
2) No stone can exist more than four times (rank 1), twice per type (rank 2) or once (rank 3 and 4) on the same base. 
3) No base can contain either no stone or more than 4 stones (the royal base can never contain more than 2 stones or less than 1). A royal base can never contain more than one rank 3 stone at any time in the game. And it can never cantain a rank 4 stone at any time.
4) At setup no base can contain a rank 3 and a rank 4 stone at the same time. This does not apply for taking or for dropping later in the game.

B) Moving bases
1) White moves first then black in an alternating way as in chess.
2) Each player can move only one base per move 
3) Each base moves and takes the way its stones allows.
EX: A base containing a W, a E and a F can moves like a W, E or a F but not like a C, D or an N.
4) Three time move repetition is a loss for the player which accomplish this first.
5) The royal base can not enter squares being unter attack by opponent bases. this is like in chess. But when there is a rank 2 or 3 on the royal base it can jump over treathened squares.

C) Taking
When a player takes an opponents base with his one this happens in this order: 

1) The defending base returns empty to his owners storage.
2) The offending base is put on the defending base place. (This is like in Chess, when you take a piece)
2) The player select, which stones of the offending base and of the defending base he will put in the offending base. With some limitations:
2a) Same rules apply here as in rule A2 and A3 as in the setting up. Exception: Rule A4 does not apply now: It is possible to put one rank 3 and one rank 4 stone into the offending base.
2b) Never be more than four stones (two for the royal base) on the base.
2c) You can not have less stones in the offending base than before the taking.
3) All left over stones are placed in the opponents storage!
EX: You takes with a JFW a JEW. Now you have 2 J, 2 W, 1 F and an E. You need to put at least 3 stones in your base due rule C2c. And you can not put 2 of rank 3 pieces in that base (There is only 1 rank 2 piece around). The base could look like this: JEFW (Jumper, Elephant, Ferz and Wazir)  after finishing the taking. In this case a J and a W will be put in the opponents storage. (Due a change in the rules these are possible also: JFWW or JEWW)

D) Dropping
You can drop bases back to game but there are some limitations and rules:
1) The base can only be placed on an empty square
2) The base must contain at least one stone and at most 4 stones. Rules A2 and A3 apply for the setting up of the dropping base. This is similar to the setup phase but there can be one rank 3 and one rank 4 on that base.
Therefore rule A4 does not apply for dropping bases.
3) This counts as a move.
4) Is is allowed to check or checkmate with a drop.
5) It is forbidden to place stones in bases already being on the board.
That means only bases in the storage can be fitted with stones and then placed on the board.

E) Checking.
1) This works like in chess. The royal base can not enter squares being attacked by opponent bases.

F) Winning:
A player wins if one of these conditions occurs:
1) Checkmating the opponent
2) Stalemating the opponent
3) Reaching the opponents royal base starting position which contains the circled square with his own royal base. Remember that entering of that square is not allowed if it is being attacked by an opponents base.    

G) Special moves
If a players base lands on one of the two opponents red corner squares (a7 and g7 for white, a1 and g1 for black) it allows that player to remove one stone from the opponents storage and placing into his own storage. This counts as a full move. Having both corner squares occupied will not help more.

H) Turns (summary):
A player can do one of these per turn
1) Move a base (Rules B)
2) Taking an opponents base (Rules C)
3) Dropping a base (Rules D)
or 4) If at least one on the opponents corner square is occupied: Moving one stone from the opponents storage into own storage. (Rule G)


I) Notation: uses the standard chess letters and signs for the notation with following exceptions:
1) The letter with the longest range piece is coming first, the two range stones coming second and the one square range letters coming last.
(J - Z - C - E - N - D - F - W)
EX: A base containing a J, a D, a N and a F will be notated as JNDF
2) The R for the royal base is every time at the beginning of the base description.
EX: REW is the royal base containing an Elephant and a Wazir stone.
3) At the beginning every player notes his pieces behind the word "Setup:" with the @ sign, separating with the commata, begining with square a1 then b1 and so one till g3. Black begins with a7 then b7 and so further till g5): EX: Setup: D@a1, JE@a2,F@a3 and so on. 

Additional letters:
@ = drop. EX: EDF@a4 = A base containing Elephant, Dabbaba and Ferz stones is dropped at a4.
& = becomes. This letter is just used in a taking move.
/ = returned to opponent storage. Again this is only used in a taking move.
EX: EDFWxa4 &JEDF /DW  This means: a EDFW takes on a4 becomes a JEDF and returns a D and a W stone to opponents storage
% take a stone out of opponents storage and put it in own storage
EX: %S takes a S stone out of the opponent storage and put it in own storage

Notes

V 0.2a
Added 2 further stones: Zebra and Camels
Removed all compound pieces because with the added pieces it is no longer possible to prevent 4 letter pieces. And these pieces are no longer necessary.
Changed all piece names to standard variant names with the exception of Jumper and Elephant. (The Jumper is a new piece I did not found in the piece encyclopedia. And Elephant is more common than Alfil.)
Fixed some small errors in the rules.
Fixed several typos.
Fixed a confusing error.

Coming soon: Graphics

V0.3: Improved the weaker pieces by allowing them to stack. For this the stones are distributed into 3 ranks.

V0.4: Removed a typo. Adeded rank 4 and distributed rank 3 pieces to rank 3 and rank 4. Rank 4 stones not allowed on royal base. Rank 3 and rank 4 stones not allowed on same base at the setup phase of the game.