Implosion, Contraction, and Moore-Tachikawa

We give a survey of the implosion construction, extending some of its aspects relating to hypertoric geometry from type A to a general reductive group, and interpret it in the context of the Moore-Tachikawa category. We use these ideas to discuss how the contraction construction in symplectic geometry can be generalized to the hyperkähler or complex symplectic situation.