Summary of "Impossible Chess"

Impossible Chess (video) — Summary

What the game is / storyline

Impossible Chess is a puzzle game about identifying and creating “impossible” chess positions — board configurations that could not have occurred in a legal game of chess. The video presents the game as a new entry in a series of indie projects by BCAT (developer of Portal Snake, Frackactory, Squishcraft). The narrator compares its rough visuals to those earlier titles while praising the clever puzzle design.

Most of the video shows the creator playing through levels, testing positions, and explaining why particular setups are or aren’t reachable in normal chess.

Gameplay highlights demonstrated

Core mechanic: place (or sometimes erase) pieces to produce a position that is impossible to reach by legal moves.
Puzzles rely on chess-specific constraints such as:
- pawn structure and captures
- piece colors (for example, bishops on certain color squares)
- promotion possibilities
- double checks and discovered checks
- parity/turn-order issues and the identity of the last mover
Types of levels shown:
- Simple impossibilities (e.g., pawns on starting rank, two kings, bishops on the “wrong” colors)
- Parity/tempo puzzles involving knight/rook/king interactions and simultaneous checks
- Promotion-based puzzles (where multiple pieces of the same type could be explained by promotions)
- Some levels were patched or changed in updates, adding or removing starting pieces
The player often uses an external analysis board (referred to in the video as “Lee Chess,” i.e., Lichess) to validate or refute proposed positions.

Key strategies and tips (how to reason about impossible positions)

Always consider promotions: promoted pawns can explain extra queens, rooks, bishops, or knights — don’t assume duplicates are impossible until you rule out promotion sequences.
Count captures and pieces: if the number of captures required to produce a given arrangement exceeds the number of enemy pieces that could have been captured, the position is impossible.
Check whose turn it is: “White to move” or “Black to move” is a crucial clue — try to reconstruct the last move to see if a legal last move exists.
Look for double checks and discovered checks: these often restrict possible last moves (a double check generally implies a piece moved and uncovered another checking piece).
Use parity and move-color logic for knights and other piece maneuvers: knights alternate square color with every move; certain arrangements require impossible parity swaps.
If all original pieces remain on the board (no captures shown), treat the position as requiring zero captures — this greatly constrains how pieces could have arrived.
Test hypotheses on a chess analysis board (e.g., Lichess) by attempting to reconstruct backward moves to confirm or refute possibility.
Remember the game may allow erasing pieces as well as adding them — consider both modes when solving a puzzle.

“White to move” or “Black to move” is often the key hint — reconstructing the last move can reveal whether a position is legal.

Notable examples discussed

Bishops appearing on the “wrong” color or trapped inside pawn chains.
Double-check positions that seem impossible because no valid last move could simultaneously produce both checks.
A pawn-capture sum demonstrating impossibility: a full line of pawns that would require far too many captures to explain any promotions.
A final puzzle presented as an endscreen challenge where it’s explicitly White’s move, yet no plausible Black last move seems possible.