Tenjiku Shogi: The Wild Variant

Tenjiku Shogi (天竺将棋) is played on a 16x16 board with some of the most powerful variants in any game, pieces that can jump over almost anything, pieces with a barrier of flame around them, and pieces that can make other pieces disappear without moving. Games are so tactical that despite the board size few games last more than 20 moves. Before moving on to explore all the fascinating things about this game, I'll review a few of the most powerful pieces that play a major part in the opening. 

First there are the so called range-jumping generals. They all move like normal ranging pieces, but can also capture by jumping over lower ranked pieces, in the following hierarchy: 

1. King, Crown Prince
   This means that you can't jump over your own king to capture something.
   
2. Great General
   Moves like a jumping queen.
3. Vice General
   Moves like a jumping bishop but with a 3-square area move.
4. Rook General, Bishop General
   These are equal in the hierarchy, and move like jumping versions of their respective ranging pieces.
5. Every other piece on the board

If these weren't crazy enough, there is one piece more powerful than them all: the fire demon (火鬼). It moves like the free boar from Chu Shogi (a queen minus vertical movement), but it also has a 3-square area move like the Vice General (abbrev. VG).  To top it all, at the end of each turn, it burns (takes off the board) all adjacent opposing pieces! In addition to this, if an enemy piece ends its turn adjacent to an opposing fire demon, the piece burns without the fire demon side having to make a move. This is called a passive burn.

 Ruleset Considerations

Being a rare game described only in a few documents, there are some ambiguities concerning certain pieces' movements, in particular the Heavenly Tetrarchs (四天王, "four heavenly kings") — plural because it is possible to have four of them —, for which there are quite a few possibilites, and the Free Eagle, which may or may not have a cat sword (diagonal one step) igui move.In addition to these two there is the lion hawk, which George Hodges (an authority on big shogi who has sadly passed away) considered to be a bishop + 2-square area move. However, the game is according to Colin Adams more interesting with the LH being a lion+bishop, and because the wording ("moves like a lion" doesn't necessarily mean that it has lion power, but it could) is very ambiguous, Richard's PBEM server (practically the only place where Tenjiku is played) uses the move suggested by Adams. 

Before the early 2000s, the jumping generals could not jump over or capture higher ranking pieces. However, analysis led to the conclusion that this gave Sente an advantage equivalent to having an extra free king (proved by the fact that in that ruleset a free king could be won by force), and although Colin Adams tried to prove that the game was still playable for gote, the rules were changed. 

Gameplay

This, however, was a double-edged sword. Now the game was more or less balanced, with Sente still having an advantage, but the opening became more or less a struggle to not get checkmated, with checkmate being achievable faster than in chess.

In the position above, although it is gote's move, checkmate by moving the VG to 8l followed by moving the GG (Great General) to 8m is unavoidable. After some 15 years of development, and yearly tournaments where these openings were put to the test, the opening has become very theoretical and well-analyzed. All of the main variations considered playable and mostly sound today were collected in a book written by Nikolas Axel Mellem, a Norwegian who is by far the strongest Tenjiku Shogi Player.