OVERVIEW
============
This chess variant is called Minihouse, and was inspired by Minishogi, a popular Shogi variant.
Minihouse is played on a 6x6 board with crazyhouse rules, with each side having one of each a king, rook, knight, bishop, and pawn in a rotationally symmetric configuration. The smaller board size combined with dropping captured pieces back on the board makes the low number of pieces still feel dense and impactful. As well as leading to shorter, but still quite enjoyable games.
DEVELOPMENT PROCESS
=======================
My goal when I began developing this variant was to recreate the feel of Minishogi, while still maintaining its identity as a chess variant, not a strict recreation of Minishogi.
In Minishogi players start with a king, a pawn, and 4 pieces: a rook, a bishop, and two other pieces that are essentially worse kings. I decided I was going to try really hard not to include any faerie pieces as I still wanted the game to be in the spirit of "chess but its trying to mimic Minishogi" instead of something like "Minishogi but its on chess.com" and introducing new pieces might make it more like the original, but not as easily digestible for people who have only played regular chess.
The board size unfortunately has to be an even number tall, otherwise chess.com will make the pawn promotion asymmetric and janky. So 6 tall was pretty much the only option. I think there might be a good game to be found on a 5x6 board, but I wanted to maintain symmetry and bishop placement would become a foreseeable design problem if I kept the opposite parity width and height, so 6x6 was settled upon.
I spent a some time with Fairy Stockfish looking at various starting positions that might work to make the concept of Minihouse fair and interesting. I decided that I definitely wanted the crazyhouse ruleset as well as starting with kings in opposite corners with a pawn in front of them. From there, I was open to many possibilities. I though about what pieces should be included and where their starting positions should be.
Queens pretty much always gave white an immediate sizable advantage, And even if I could find a more equal starting position, playing with them would probably be too oppressive, on such a small board they are usually controlling more than half the squares, and I didn't really want to add more pawns, so king safety would likely become too hard to maintain.
I was originally against the idea of having only a single bishop per side as you could only put 1 bishop on 1 color. But in many early layouts have 4 pieces per player felt like there was too much going on, and I didn't really want to exclude a rook or knight. I settled on having a light square bishop as the king starts on a dark square, making immediate forcing openings involving bishop checks not possible. That left 3 squares to choose from. The corners obviously didn't make sense as they could capture each other on move 1. The square next to the king also felt a bit too rigid, it defended and attacked the respective pawns, so you probably didn't even want to move it. That really only left the square it is on in the final version.
The rook is going to be at least a little active wherever it starts. I though it best not to put it directly in front of the king as in Minishogi, given chess's lack of low value defensive pieces. In the final arrangement it is not able to immediately capture a piece, and although it can immediately make a threat to capture the bishop, the opponent has plenty of ways of dealing with this.
Similar to the bishop, the knight was placed on its least active square. The geometry of its starting spot makes it so even after a move or two it is not able to target the opponents most valuable squares. (For example even in the corner it could move and immediately pressure the opponents pawn, possibly forcing a defense or a push. If placed on the square next to the king it could immediately move and restrict the opponent's bishop.) Given its placement on a dark square, it needs a developing move to start controlling dark squares, important considering (at least at the start of the game) there are no dark square bishops.
Looking at the final version, I am very happy with the pieces placement overall, starting closer to the king as they are initially less active and more defensive, also visually and thematically it feels nicer than if they started apart. Further, none of the pieces restrict the opponent's pieces too much at the start, allowing for a variety of opening moves.
Promotion mechanics in Shogi are quite different from in Chess. In Minishogi, the pawn mostly serves as a defender for the king, getting it to the end of the board is a lot of work, and even if you do, a promoted pawn is not too amazing of a piece. In chess, promoting it is still a lot of work, but promoting a pawn is a vastly bigger gain in material than in Shogi. I was expecting the gameplay implications of this lone past pawn in front to the king to be quite different from Minishogi, and I was quite content with this difference and excited to see how it would play.
I did play a few test games where the pawn could become a queen as a powerful promotion is a staple of chess's mechanics, but far to often it would feel completely reasonable to sacrifice a piece for the pawn and then dropping it on the next move one step for promotion. This did actually lead to some interesting games, scrambling to stop the promotion and/or protect your pawn. I think including something like this might make for an interesting chess variant, but here I felt it took too much focus away from the original concept, so I decided to limit promotion to rook, knight, and bishop.
The final version of the Minihouse is evaluated by Fairy Stockfish as being slightly in whites favor on low depths around 20 to 30, declaring it dead even after about depth 40, however then turning around and giving +0.1 at depth 60+. I thought this was actually quite a good evaluation to have. With the smaller board/pieces it was quite likely for the engine to call it a draw, but requiring it to need to look fairly deep to do so made me hopeful that this would be a successful position.
TESTING
==========
Over the course of the last few weeks I have played many, many games of this with random people on the internet.
I am only 1600 blitz, so I am not sure what much better players might experience while playing this variant, but while testing I found that, even with this limited board, there were many opportunities to blunder. Further, a seemingly game losing blunder could still be recovered from (for instance dropping a piece and recovering some material through a fork or pin). In short, even with the small board, the game was still complicated enough to feel interesting and captivating.
Like I was aiming for, I found that the king is initially quite safe. Is is not possible to take advantage of the open diagonal without first capturing and dropping a new bishop. The starting position of the pieces are quite uncoordinated to begin with. The knight and rook are in awkward places to start attacking right away, sometimes requiring multiple moves to get into a good position. The bishop can be activated fairly easily, but it's not going to accomplish anything on its own, and if desired, can be easily contested and/or traded by your opponent. While both players both start with a past pawn, pushing it immediately does not seem to be the best idea, and even in a worse case scenario giving up a piece for the pawn is not game losing. That pawn could come back and fork or promote.
One of the subtler nuances of Minihouse that I appreciated in my testing was the dynamic between the value of the bishop and the knight. Trading your knight for a bishop led to you being able to acquire the bishop pair, which could be used to great effect on this open board. Knights could also be more valuable than in normal chess as a result of the smaller 6x6 board, their short range movement was relatively less of a handicap. And as in regular crazyhouse, having a knight in hand to drop to potentially fork anywhere on the board was also an excellent strategy.
One notable change from Minishogi that I am quite happy with is the pawn. Seemingly it is no different, the pawn is in front of the king, and is one square further from promotion. But as said before pawn promotion in chess is much more impactful. Promotion became a great secondary strategy if both players were defending well. As well, not allowing a queen lead to more interesting decisions when it came to promoting the pawn. While in many positions you'd want to just make the best piece, the rook. Quite often you'd want to consider the other two options, for example promoting to bishop to immediately control the opponent's "queening" square.
I initially had the time control at 1+1 and later shifted toward slightly longer bullet and blitz time controls. I do think playing on faster time controls would be more enjoyable once who've gotten a feel for the variant, but really time control here is much more about the preferences of the players.
The games were quite short, 10 to 20 moves on average, and I feel this added to the enjoyability, they were like little bite-size games, that seemed to leave many of the people I played with wanting to play a few.
As the ruleset includes crazyhouse, though there are only 10 pieces total on the board, none of them will ever leave the board for good. Normally, the crazyhouse variant on the standard chess board tends to lead to quite a lot of sequences of dropping pieces for devastating attacks. However, I've found with the limited number of pieces in this variant, crazyhouse rules end up having a bit of a different feel. Often it was more about setting up your other pieces to make a single drop very impactful. The coordination of pieces on the board ends up playing a bigger role in deciding games. Further, having pieces in hand means you have (relatively speaking) much less material on the board when compared with regular crazyhouse, and as a result, hoarding pieces to unleash in all at once is a much less effective strategy.
DOS AND DONTS ADDRESSED
==========================
1. Fairy Stockfish evaluates the starting position as fairly even for many different branches of moves. From play-testing, both white and black have plenty of chances to seize advantage during the game. As seen in my opening analysis in my comment below, there are plenty of valid opening lines with only a few traps a new player might fall into, none of which are instantly game losing.
2. As said earlier, initially the king is very safe. There are no captures or checks on move 1, and while there are two moves that immediately threaten to win material, black has a wide variety of reasonable responses to choose from.
3. N/A
4. As described during the development of the mode, pieces were placed in their starting positions to be as inactive as possible. But since the board is small and open, this will likely change quickly after a few moves. From testing I've found that while it seems attacking pieces may be limited, defensive resources are also slim. Especially with the potential of trading and then dropping pieces, allowing the player with the initiative to potentially get their pieces back on the board first as part of their attack. The variant definitely requires careful planning to make good use of your somewhat limited resources, but it's not too difficult to get going.
5. I would say that this variant is quite chaotic and fast paced, with the small open board and crazyhouse rules. While the king is very safe for the first few moves, maintaining this can be quite difficult. One can definitely place their pieces in a defensive manner, but often it is more about attacking before you can get attacked yourself. However! I believe very strongly from play-testing that this chaos is to the variant's benefit, and makes for an enjoyable playing experience.
6. As discussed previously, there is an alarming variety of opening moves for such a seemingly limited board. As well, once pieces are traded, dropping leads to an even larger number of possible games.
7. I think it is clear from the development section that the pieces and their placements were quite thought out.
8. The goal is checkmate, and for most chess players, I am sure this will be an easy goal to grasp. Dropping pieces to aid in attacks should also not be too difficult to understand. Promoting the pawn and winning material can also be intermediate goals to aid in attacking your opponents king.
CLOSING THOUGHTS
===================
I was pleasantly surprised by the amount of people who wanted to play several rematches, I did put a good bit of time into constructing this exact position, and I thought my enjoyment of playing the variant might come from my own bias towards it, but it seemed like the random players that were testing it with me liked the concept and enjoyed playing.
I hope everyone has a good time playing this during opening testing, I am definitely open to critique and changes. I have absolutely no preference on the default time control, so definitely try out a bunch and see what works best. I think adding pieces like the wazir and/or ferz might make some more defensive styles of play viable similar to the generals in Minishogi and might also allow for more piece drop combos to be pulled off. However they could end up making the game too hectic or too slow and drawish. Also allowing promotion to queen still might be a fun idea, but might more often be pretty much game winning to promote, rather than the fairly moderate advantage it is now. And of course any other ideas you might have to improve Minihouse are welcome and appreciated.
So sorry about the long post, it probably got a little rambly. I just spent a lot of time thinking about this variant and wanted to get all my thoughts about it out there. Thanks so much for taking the time to read this! I hope everyone gives Minihouse a try.
Opening Appendix
================
Opening moves are surprisingly diverse for such a small board and piece set. Most of white's moves that don't immediately hang a piece are completely reasonable moves to start. As well black's responses are adequate and varied. Played well, there is not way to force an immediate positional or material advantage. Further, once pieces are exchanged and dropped back on the board, the variety of games becomes quite apparent. Let us explore a few moves in a few potential opening lines.
NOTE: Notation is as if the outer ring of squares on a standard size board were inaccessible. For example b2 is the lower left corner and g7 is the top right.
1. Bc4
------
Threatening to win an exchange and by far the most common opening move others played in my testing.
..Rf5
..Rf2
Any other rook moves here feel clunky as it can be an easy target for white and they are not attacking anything, but they're not necessarily bad for black.
..Rf4? 2. Kc3
Rf4 puts pressure on white's bishop and prevents the knight from moving, and most of white's responses lead to black having the initiative, but white can play Kc3 followed by Rb2 next move and enjoy a nice position, ready to push the pawn.
..Bf5 2. Bxf7 Bxc2? 3. Bc4
A straightforward response at first, trading the rooks instead, but here white is threatening checkmate by dropping a rook on f7. This can be avoided without black losing any material by playing Kxf7 on move 2, appearing to lose an exchange, but no matter what seemingly good move white plays on move 3, black can drop a bishop checking the white king forcing the rook to block, allowing material to remain equal.
1. Rc7
------
Immediately attacking the undefended bishop.
..Be6
..Nd5
..Nf5
Are all straightforward responses to the threat. White has many ways to continue development.
..Nc6
Is also ultimately fine, but can lead to black quickly losing a piece if they are not careful.
..Rf2 2. Rxd7 Rxe2
Trading instead of defending the bishop also works.
..Bf5 2. Bc4
Appears to lead to white winning an exchange, however black will be able to drop the recaptured bishop with check forcing a rook to block.
1. Ne4
------
Is the move recommended by the engine. Puts the knight on a central square and restricts black's pawn and rook. However overall, a very tame, positional opening move.
..Bf5
..Rf4
Contesting white's very nice knight. Usually followed by Bd3.
..Nd5 2. Bc4 Be6? 3. Ng5
Black saying "I want a nice knight too." Bc6 (instead of Be6) is the only move for black to not lose material.
1. b4
------
Immediately starting towards promoting the pawn. Many of blacks natural responses lead to advantage for white, but if played will by black gives white many opportunities to blunder. Playing for equality against black's best moves requires not pushing b5 too soon.
..Rf4 2. b5? Rb4+ 3. Kc3 Nd5+
Lead to white losing the pawn.
..Nc6 2. b5 Nd4 3. Bc4 Nxc2 4. Bxf7 Bxb5 5. Bxg6
This is a very tricky line, after playing b5, this is the only line where white can come out even. Black's real only opportunity to blunder is if they try to capture the bishop on move 4 it seems then that black keeps the pawn advantage but white can play b6 instead of recapturing the knight and white will be the one who is winning.
..g5
Symmetrical pawn push opening will give advantage for white if continued as white can play b7=B, controlling the promotion square of black's pawn.
1. Nc4/Nf3
------
A bit of an off-beat opening, moving the knight less centrally, but can quickly lead to being able to trade the knight for the bishop if black moves their knight as well, gaining the bishop pair, which can be quite powerful on the open board.
Timecontrol
3 minPromotion
Bishop, Knight, Rook on the 10th rank