The discovery of the 'hat' tile in March 2023 solved a long-standing problem of forced aperiodicity with a single shape, but it required both handednesses (reflections).
Two months later, the same authors announced the 'Spectre' tile, which can tile the plane with only one handedness, addressing public criticism.
The Spectre tile is similar to the hat but has all edges the same length (with angles of 90° or 120°) and is a 'weakly chiral' aperiodic monotile; edge constraints make it 'strongly chiral'.