  I review the covariant quantization of the critical $N{=}2$ fermionic string
with and without a global ${\bf Z}_2$ twist. The BRST analysis yields massless
bosonic and fermionic vertex operators in various ghost and picture number
sectors, as well as picture-changers and their inverses, depending on the field
basis chosen for bosonization. Two distinct GSO projections exist, one
(untwisted) retaining merely the known bosonic scalar and its spectral-flow
partner, the other (twisted) yielding two fermions and one boson, on the
massless level. The absence of interactions in the latter case rules out
standard spacetime supersymmetry. In the untwisted theory, the
$U(1,1)$-invariant three-point and vanishing four-point functions are confirmed
at tree level. I comment on the $N{=}2$ string field theory, the integration
over moduli and the realization of spectral flow.
