O2 CubeThe slice cube implemented in something that does not look like a puzzle.
O4 CubeA Mixup Cube with all corners bandaged together and hidden in what does not look like a twistypuzzle.
Offset SkewbA Skewb with rectangular centers and four enlarged corners.
Oh CubeA puzzle looking like a 3x3x3 but it is indeed a corner turning hexahedron.
Oskar's Danger CubeAn extension of the Caution Cube or Geared Mixup concepts - this time with more types of moves possible.
Overlapping Cube VariantA simple Overlapping Cube with an additional set of four edges exposed. This puzzle turns like a cuboid not a cube.
Pandora CubeWorks like a 3x3x3 but with challenging new exterior.
Pandora Rainbow CubeA straightforward and beautiful shape variant of the Rainbow Cube, inspired by the Pandora Cube.