We describe a class of 2d TQFTs whose values are hyperkähler cones. Namely, to a Riemann surface with boundaries is associated a hyperkähler cone with isometry $G$, and gluing corresponds to the hyperkähler quotient with respect to the diagonal $G$ action. The possible `values' include flat hyperkähler spaces and moduli spaces of $E_n$ instantons. Various properties of this TQFT are `calculable' in terms of an M-theory construction. Mathematicians are urged to construct them rigorously.