Restricted 2x2x2x2x2¶
Restricted 2x2x2x2x2
4D Shape: Penteract
Physical Shape: Rectangular prism
Pieces: 32 5c
Magnets: 768 (without buffer)
The restricted 2x2x2x2x2 or 25 (also called the physical domino reduced 2x2x2x2x2) is a physical puzzle that represents the state space of a virtual 25 puzzle, with one of the axes only being able to do 180 degree turns. This puzzle is like the 5D equivalent of scrambling a 23 with only <U,D,R2,F2,L2,B2>, which makes the solve way easier than the non-restricted version.
The first known restricted 25 was made by Grant Staten which he showed off in a YouTube video. Hyperespy also made a version using foldable paper cubes to cover the pieces.
Pieces and Twists¶
There are 32 5c pieces, but each piece can only be oriented in 12 ways instead of 60 because of the axis restriction. And just like Melinda’s physical 24, this puzzle has certain legal moves that a solver must follow. Each twist of this puzzle is like rotating a tesseract. You can take off half of it and do any reorientation like you would on the physical 24. This includes simple rotations and gyros. The only thing you can’t do is a 90 degree twist of the square layers (this results in a legal puzzle state, but is not analogous to any move on the virtual 25). See Hyperespy’s video for a full overview of the canonical moves and a way to scramble the puzzle quickly.
How to make one¶
Buffer pieces magnet layout
Order a 24 DIY kit from Melinda Green. Then assemble it with a mirrored colour scheme from your current 24, but with the same magnet layout. For the 5D stickers 192 are needed in total, with half (96) of them being black and the other half grey. This means that each normal physical 24 piece gets 6 stickers on it. A good option is to order a couple of custom sticker sets online such as these.
Grant used buffer pieces when making his version in order to make it obvious to avoid doing illegal twists. If you want to add buffer pieces, you need 8 monocolored hypercubies with a custom magnet layout. Although there’s only a few different illegal twists that are even possible so it’s not too tricky to avoid altogether.