How deep is your madness?
Let's get this out of the way first. Inferno Chess is simultaneously named after Dante's Inferno (levels of hell, it'll make sense once you read the rules. Or hell, it might make sense just looking at the board), and the 1970 Doctor Who story "Inferno" which is set in a parallel universe.
What is this?
At it's core, this idea simply nests Chess boards, and provides a mechanism for moving between nested levels, and covers other contingencies (like winning). It could be applied to many (certainly not all) Chess variants. As described here, we'll be referring to standard chess as the reference.
The concept does not have any limits to depth, though "infinite" is nonsensical and any large number of levels be impractical (for physical and/or gameplay and/or sanity reasons).
All discussion here will be based on a sample board of depth 5.
Any of the following could be used:
- Multiple normal chess boards (one per layer) and some notes to synchronise levels.
- A single customised chessboard, and appropriate custom pieces to suit the levels.
- An as-yet-nonexistent software version of this which would handle a lot of this
Inferno Chess expands on algebraic notation with a simple prepending of a digit to indicate level of move. The sample board on this page has five levels. I'll concede here that I don't know algebraic notation well enough to be certain that this avoids all ambiguation, but it shouldn't be difficult to fix that (eg, by indicating level within braces).
More generally, the board should be visualised as having a "hole" in the middle 4x4, within which sits a whole new board. Using the hole metaphor, this is a deeper level, and then recurse the idea to taste. This concept of "depth" is used in the rules, especially regarding "descending" and "ascending"
- Setup is simple. Normal chess setup on every level. Note: this means the number of pieces each player controls in total, is 16x the number of levels. So on the depth5 example board here, there are 80 pieces per player to setup.
- On each level, the normal movement rules of chess nominally apply. However, if any piece ends on the center 4x4, then it descends into a deeper level.
On any turn, a player plays only one piece from only one level of their choosing, and then it's the opponent turn. At any time (including the first turn) a player may choose to play at any level. Normal chess "must resolve check" still applies however.
Descending is easy. When you land on an inner 4x4 relative to your current board, you descend to occupy a location on any sublevel within your original target square. eg, if you move to 1D3, that is within the inner 4x4 and has four possible target locations: 2C2, 2D2, 2C1, 2D1. The center 2x2 have many more targets each (how many is dependant on how many levels there are below the current level). In a 5 level board, then 1D4 has: 12 targets on level3, 12 targets on level4, and 16 targets on level 5. That's a total of 40 target positions that a piece on level 1 moving to 1D4 can occupy. The mechanism works from any level. 2F5 has 3G6, 3H6, 3G5 and 3H5 as targets. 3D4 has 16 targets within level 5...
There are some rules that still must be adhered to when descending
- You must respect original position colour rules. ie, bishops remain colour locked, knights always colour swap, and pawns colourswap unless it's an initial double move, or taking another piece on the diagonal.
- If a target position is occupied by your opponent, it may be taken and treated as a normal taking move. Empty positions are naturally available to move to also.
- Positions occupied by your own side, may not be replaced.
- Kings are the only piece that may not descend, nor can they be taken by descending. They can be put into check or checkmate by a piece descending however.
Descending can occur on any move, including to create or resolve check on a lower level. The normal chess rule prohibiting putting yourself in check still applies.
If a level is won, and there is a higher level, then ascension occurs and pieces move up to the next level. There are several ascension rule options, and all are listed here pending playtesting to determine which provides the most balanced game.
Common to all rules:
- Kings do not ascend (just as they cannot descend)
- Any lower levels relative to the won level numerically improve by one - all pieces improve a level. This way there is always a consistent stepping of active levels. This is ascension by level as a whole does not impact any other levels.
- If level 1 is won, then all pieces from both sides become inactive (nowhere to ascend to), and all lower levels improve their level number numerically. This effectively just removes pieces from both sides and is not expected to tactically useful
- The ascension is considered part of the turn of the player who won the level. Only at the end of an ascension does it become the other players turn. However, if they are already in checkmate on the next level, then another ascension occurs. Chained checkmates are considered theoretically possible.
Ascension rule in flux are in pairs thus:
Which side ascends
- Winning side only
- Both sides
- Ascend to relative algebraic position (eg 5D3 -> 4D3. 5A7->4A7, etc). Relative position ascension requires rules to manage conflicts at time of ascension:
- Conflict won by the piece on the upper level that is already in that position (it's the relative godlike piece afterall)
- Conflict won by the ascending piece (in a "move" type manner)
- Conflict won by active player choice (it's assume they'll pick the best piece when it's a self-conflict, and their own piece when against the opposition)
- Collapse each 2x2 locations that map to the absolute position on the next level up, and ascend into the upper central 4x4. (eg: 5A2, 5B2, 5A1, 5B1 all collapse into 4C3). This requires some rules to manage collapsing squares before that square ascends
- Active player chooses which piece to win each 2x2 collapse across the whole board
- Collapse is won automatically by piece ranking (eg: Queen beats Bishop beats Knight beats Rook beats Pawn). tiebreak to the winner of the level.
- Each player chooses which piece to win each collapse if there is no conflict between sides for the collapse, in which case the winning player chooses.
Note: there should be notation to indicate level renumbering. This has not been considered.
Current thinking is to prefer:
- Both sides ascend, into absolute positions, with 2x2 collapsing done by each player where possible.
TL;DR of Ascension and Descension
- Individual pieces descend in a highly targetted manner, godlike from above, one per turn at most.
- Whole sides ascend in an untargetted manner, like a mass uprising from below. A whole winning side in a turn.
As the game progresses, levels are effectively removed from the game as each is won.
Check and checkmate itself can only occur from pieces on the same level, but can occur by attacks "across" the hole. Indeed, the lack of ability to place pieces in the center 4x4 may make check more plausible in some situations! Each level should be considered to only have a conceptual view of itself and any sublevels. Pieces on higher levels do not create check (or castling-blocking through-check) situations.
It's expected likely that the deepest level will resolve first and then each level upwards in turn but is not required and this prediction may be wrong.
Once the board resolved to a single level, the game finishes as per normal chess
Note: due to per-level wins, these may also be tracked as a running score, but this author feels that they are mere battles in the war and the final battle than ends the war is the only one that really counts.
It's expected that the two main tactics will be
- try to keeping pieces at higher levels for late-game deployment to lower levels to squash uprisings, and
- send pieces into lower levels early to win and create an unstoppable uprising
It's impossible to say yet which is better in general, or what other tactics and styles can counteract each of those main tactics.
The nature of the rules means "descending" dominates the early game, and "ascending" only occurs late-game (afterall, ascension only occurs at the end of any given level)
Misc other notes and thoughts
- This is considered at a whole-game perspective, so even if an individual level is stalemated, so long as the player can make a move somewhere else, the game does not end in stalemate. Stalemates are still possible for situations where a player is not in check on any level, but any move by any piece (including all possible descensions) creates a check, then the game ends in stalemate. This is theorised as being very unlikely.
This game was inspired by Dakotah Sky Walker on facebook and their posting of an image showing an infinite depth board of this style, representing their descent into Chess research. From this I took the board literally and began pondering how to craft a real game around it, including a first draft of this idea.
The original post no longer exists, but their image was shared again in a comment to my initial fb tease post about Inferno Chess: https://www.facebook.com/nemothorx/posts/10159641848278216