  I give an overview of open, closed and heterotic N=2 strings. At the tree
level I derive the effective field theories of all the strings, and discuss the
group theory of the N=2 open string and the interaction between its open and
closed sectors. At one loop N=2 string loop amplitudes and partition functions
have incurable infra-red divergences, and show puzzling disagreements on the
dimension of spacetime when compared to their effective field theories. I show
that the closed-string three-point amplitude can be written directly in terms
of a Schwinger parameter, so explicitly exhibiting the inconsistency. I finally
discuss the possibility that the puzzles posed by the loop amplitudes could be
solved if the N=2 theories were Lorentz invariant and supersymmetric, and I
speculate on possible modifications of the string calculations.
