A Möbius strip, Möbius band, or Möbius loop, also spelled Mobius or Moebius, is a surface with only one side (when embedded in three-dimensional Euclidean space) and only one boundary. An example of a Möbius strip can be created by taking a paper strip and giving it a half-twist, and then joining the ends of the strip to form a loop.

Tic-tac-toe Collection supports playing on a Möbius strip as a topology option. When playing this way, the play space appears repeated in each direction, but flipped. For example a vertical Möbius strip has each copy of the place space flipped horizontally.