# Chess, but with gravity? #1

Based off of this puzzle and this Youtube video

Rules:

• You control the pieces labeled kn (knight), b (bishop), and r (rook)
• You are trying to capture the piece labeled ok (opponent king)
• Walls can be jumped over by knights, and floors can be passed through in any direction by any piece but cannot be fallen through.
• If a piece hits the ok, it is captured.
• Pieces fall until they are blocked by a wall, a floor, or a piece of the same color.
• ok cannot move.
• Walls and floors can be passed through by kn.

The puzzle:

+---+---+---+---+---+---+---+---+
|   |   |   | x |   |   |   |   |
+---+---+---+---+---+---+---+---+
|   | x | x | x |   |   |   | x |
+---+---+---+---+---+---+---+---+
|   | x |kn | x |   |   | x |   |
+---+---+---+---+---+---+---+---+
|   | x | x | x | x | x | x | x |
+---+---+---+---+---+---+---+---+
|   | x |   | x |   | x |   |ok |
+---+---+---+---+---+---+---+---+
|   |   | x |   |   | x |   | x |
+---+---+---+---+---+---+---+---+
| b | x |   |   | x |   |   |   |
+---+---+---+---+---+---+---+---+
| r |   |   | x |   |   |   |   |
+---+---+---+---+---+---+---+---+


Now my question to you is:

## What is the minimum number of moves needed to capture the opponent's king?

• For an online game based on this, see this game in Armor Games: armorgames.com/chessformer-game/19096 Commented Dec 11, 2023 at 4:24
• "If a piece hits the ok, it is captured." - which is captured, the piece or the ok? Commented Dec 11, 2023 at 11:32
• can the rook and bishop also pass through black squares? - on a normal chess-board one would think so ? Commented Dec 11, 2023 at 11:45
• This looks like a very nice concept allowing for quite complicated puzzles but your particular setup actually requires only one of the three figures to move and doesn't use features like figures being able to support each other. Commented Dec 11, 2023 at 12:02
• Since the question you took inspiration from has very well worded rules, you should probably copy the rules-text of the original question to your own question. It includes all rules for walls blocking movement and also about units supporting each other, which this question is currently missing. Commented Dec 11, 2023 at 13:05

The minumum number of moves appears to be

Four

• This is assuming of course that the rook cannot move through black squares (which I think is intended but not specifically stated). Commented Dec 11, 2023 at 0:17
• @CrSb0001 I mean move sideways through them, for example, so rook could go all the way over and then up. Commented Dec 11, 2023 at 0:18
• @CrSb0001 I think you misunderstand me, in chess parlance the moves would be Rh1 and then Rh4, no jumping. Commented Dec 11, 2023 at 0:21
• It should have been stated, but the black squares are walls that cannot be entered or passed through. The knight can jump over the walls per standard knight movement. @hexomino Commented Dec 11, 2023 at 0:23
• @CrSb0001 It says "unless [conditions], [effect of gravity]" Please refer to my previous comment on what should be stated. Commented Dec 11, 2023 at 0:37

# The minimum is

3

1. Knight to E5 (2 right, 1 down) -> falls down to E3

2. Knight to F5 (2 up, 1 right) -> keeps standing, black underneath

3. Knight to H4 (2 right, 1 down)

This assumes that the knight can land on black squares (not forbidden by the rules) and gravity cares only if a black field is below the knight.

• Sorry, I should have made this more clear. A knight can pass through black squares, but it can't go on the same square as a black square (due to gravity) Commented Dec 11, 2023 at 12:48