[zuxtjtzz] Wandering among hemicubes

Play a Portal-like game in a room in which passages among through walls connect to other walls.

Or on a surface of a hemicube.  Or other abstract polyhedra or polychora (11-cell, 57-cell) though I am less sure how the latter would work, as the hemi-polyhedral cells don't seem to be manifolds.

Play in 2D or 3D hyperbolic space, maybe flight simulator.