On a board like this, there are three simple ways to form a non-trivial loop, each of minimum length n:
. . x . . . . . . . . . . x . . . . . . x . . . . . . . . . x . . . . . . . x . . . . . . . . . . . . . . x . . x . . . . . . . . . . . . . x . . . x . . . x x x x x x . . . x . . . . x . . . . . . . . . . . x . . .
Vert Horz Diag
P. S. Your homework assignment (2 stars): Invent a connection game on the Klein bottle.
a) Play Projex; or b) Assign two maximally distant cells to one player and play Antipod.