CollideThree circles with 90°-turns but in different sizes.
ColondraEight intersecting circles bandaged comparable to the Rotascope.
Colors CrossTwo plungers and one rotation used to move nine pieces.
ComboSimilar in concept to a number of other puzzles.
Cor CaroliThree intersecting circles rotating around two centres.
Corner of InfinityA three circle puzzle centered on the corner of a hexagonally tiled infinite plane.
Crazy LekkiTwo intersecting circles with four rings and three different possible turns.
Crazy LoticaA reimplemented Lotica with an additional inner circle.
Crazy puzzlerFour intersecting circles, two are sixfold and two are threefold.
Crazy RodiumThe Puzzler with two concentric circles per half.
Crazy TrioFour intersecting circles with a bunch of cuts.
Crossover puzzleA puzzle back from the early 1980s produced by Nintendo. It works with intersecting plunges and polarised light.
Dancing GearsA puzzle with two intersecting circles. Produced in low quantity in four different variants.