Checkmate the Smarty-Pants"/"Smess: the Ninnys Chess"

Fun board game with simple rules.
It is a chess-like board game for two players.
The goal is to beat your opponent's brain. The type of piece determines how far you can move, and the arrows on the squares determine which directions you can move in. 

Players alternate, moving one piece, and only one, on each
turn. Each square has from one to four pointers printed
on it. Players move out of any square only in a direction
indicated by these pointers. NOTE: It is always the pointers
on the space a piece starts from, that determines the direction in which that piece may move.

A NINNY can move only one space on any turn.

To capture an opponent's piece, you move your piece onto the square it occupies.

A NUMSKULL is more valuable than a NINNY. On each turn, a
NUMSKULL can move any number of squares in any direction
a pointer indicates from the square it is on. It can move
one square, or two, or three or more, but it must move in
a straight line. It does not have to obey any pointers
except the ones on the square from which it starts.

A BRAIN moves in the same manner as a NINNY.

Players may never move any of their pieces onto or over a
square occupied by another of their pieces. A player must
move each time it is his turn. He may move any one of his
pieces he wishes, so long as it can be moved without landing
on or passing over a square occupied by one of his pieces.

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UPDATE 18.10.2025:

Need a box for the game pieces:

https://makerworld.com/de/models/1899464-box-magnet-with-hinge-85x90x34mm-print_in_place#profileId-2035575

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UPDATE 03.04.2026:

added better pictures with the rules: