time travel chess adjustments

I know that i haven’t really talked about my trip to London or posted any of the pics, but the reality is that a lot of what I want to say about that trip is featured in the Can’t Stop episode of my Babbling Rooks series, so writing about it feels redundant.

So instead we’re going to talk about Time Travel Chess – and some adjustments that I feel helps the game make more sense from a spacetime perspective and is also better balanced from a gameplay perspective.

The original Time Travel Chess (or at least the most popular definitive variant i’ve found) was developed by Gary Gifford in December of 2003.  There are detailed rules on chessvariants dot com, but the TL;DR is:

  1. Any piece touching the king can travel forward in time up to 10 moves.  No piece can time travel if the king is in check.  Execution of the time travel is by assigning the designated piece a future move number limited to one piece per ‘future move’.
  2. At the assigned move number, the player must place the time traveling piece on the board on any legal square.  If placing that piece would be an illegal move (because the king is in check and the only way to resolve it is to move the king), then that piece is ‘lost in time’ and can’t come back on to the board.  The king(s) can also move forward in time but if they get ‘lost in time’ that’s considered checkmate.
  3. The king can also move backward in time up to five moves.  They can only do that twice.  If they elect to do that, they choose the move that they’re moving backwards to and the board is restored to that state – with them placing the time traveling king as a (likely) second king on the board on to any legal square in addition to the one from the previous move state.  If they go backwards again, they have three kings on the board.  Only one king needs to be in checkmate for it to be considered a win.

It’s an interesting concept, but i think there are some fundamental issues both practically and philosophically.  Someone else thought so too and wrote about it, and that’s spurned me into thinking of my own ideas about it that I may attempt at some point in a Rooks episode or for fun otherwise.

Here’s a rundown of the issues from my point of view:

Issue #1: Restricting time travel to pieces touching the king changes the nature of the king too drastically.

In typical chess, the king doesn’t move around a whole lot and for good reason – it has the least flexible move mechanic and is what determines the fate of a win versus loss.  Entire game strategies are built around the mutual “i’m protecting the king and the king is protecting me” approach.  Restricting time travel around pieces that are touching the king thus feels counterintuitive because it forces the king to move around much more and then also poke holes in its own defense for the sake of time travel.  Maybe that means that the time travel mechanic would be something that people would choose to use sparingly rather than abundantly, but what i want out of a chess variant such as this would be for the mechanic to be celebrated and exploited for multiple purposes rather than just used as a ‘break glass in case of emergency’ situation.

Issue #2: Letting time traveling pieces pick any legal square on the board to drop seems too arbitrary and too powerful.

Sci-fi shows and movies tend to lump space and time travel as being things that go hand in hand (the TARDIS isn’t restricted to having to land in the same spot when it travels in time), but in the context of chess play it feels strange that a piece could ignore its normal move mechanics entirely by time traveling, especially if they only travel one move into the future.  The power of unlimited teleportation is tempered somewhat by the “has to be touching the king” (but see issue #1), “can’t time travel whist the king is in check”, and the “lost in time” risk.  But i think i would rather see the pieces still act like themselves in some way when it comes to time travel because that restriction feels more interesting.

Issue #3: A piece getting “lost in time” is a band-aid fix to the potential paradox problem.

The MathematRec guy stated this about getting lost in time:

Getting “lost in time” isn’t really a paradox, but it is untidy… consider that time teleportation from time t0 to a later time t1 might or might not violate some conservation law, i.e. it might or might not be impossible, and it might not be evident at time t0 whether conditions at t1 will allow the trip. So what happens if you try? Do you find you can’t, in which case you’ve received information from the future? Do you get “lost in time”, whatever that means? Do you teleport to a different time?…

In chess, a piece cannot space teleport (move) to a square occupied by a friendly piece. It doesn’t get “lost in space”, and it doesn’t end up on a square other than its intended destination; it simply can’t attempt the move at all. Information passes from the destination to the source to let the knight know it can’t move there, if you like. Likewise it seems to me time teleporting must be impossible if the result is an illegal position; in that case information passes from the future to the past, telling the past that the game situation in the future doesn’t allow the teleport.

In other words, a piece should never get “lost in time” because a time traveler who hops wouldn’t “feel” that sense of time – it would be instant travel from one to the next, and so from his perspective, he would never put himself in a position that would make the move illegal.  But the conditions to know whether that move is “illegal” or not in Gifford’s conception is not something that can be predicted in the normal timestream of events.

Issue #4: If the king moves backwards in time and gets inserted as a second or third king into the “new” original timeline, it creates a grandfather paradox.

Even without the rule of adding a second or third king on to the board, going back in time and making different moves from what happened in the original timeline eliminates the moment that motivated the king to travel back in time in the first place.  To ignore that paradox is to ignore the fundamental principle that our perception of time is an illusion and that time is actually a dimension in the same way that height and depth are.


So given those fundamental issues, how are they fixable in a way that still makes the game playable?

Rule Change 1: Allow any piece the ability to travel forward in time but place restrictions on its movement in space.

My initial thought about that was that a piece should be able to travel either in time *or* in space and not both, so if you were going to move forward in time, you’d have to reappear on the same board space.  That feels like a practical mechanic, but it doesn’t feel theoretically sound.  Another idea would to make the mechanic similar to Alice Chess.  If a piece opts to jump, they have to move in a way that’s legal for the board state at the time and then place a marker on that tile.  That square is then “protected” at that move, meaning that no piece can occupy that square at the time when the piece would drop, and that square cannot be in a state where in the turn after the piece drops the opposing player can immediately capture it.  Therefore any piece on that square would be forced to move off of it as a consequence of a time traveling piece about to materialize on it.

That feels sound to me because the knowledge of when a piece is going to drop does affect the strategy and the outcome around that time jump and therefore treats the time jump in a manner closer to the singular spacetime dimension instead of something separate, but it has one potential exploitable problem in that if a player is forced to make a move that would make that time drop legal, that means that they also would not be allowed to put their opponent in check.

[EDIT: I’ve addressed a big flaw in this rule change in this post.]

Rule Change 2: A king going backward in time reverts to that ‘save state’, but that state is an independent timestream from the original timestream.

Going back in time is not about changing the present circumstances but is instead about creating an alternate timeline.  MathematRec’s methodology of “you can only move on that reality if it’s your turn in that reality” is fine for the most part, but I also think in situations where a board’s been neglected by a player because their situation is unfavorable, it might be an interesting mechanic to introduce a “time rip” where the same player can then make a second move to put more pressure on the other player who is content with letting that board sit after x amount of moves.

Rule Change 2 Addendum: One of the two “backwards in time” uses can be used to fracture the timestream at its current point.

In other words, the king could elect to duplicate its current state to an alternate timeline.

all of this is pure intellectual speculation at this point – i’m not sure how the game will actually work in practice.  we’ll see what happens if i ever decide to rope someone into playing this with me.  it’d be a fun experiment in any case.

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  1. Pingback:time travel chess adjustments – addendum » mendel lee . com

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