  We look at intensionality from the perspective of computation. In particular,
we review how game semantics has been used to characterize the sequential
functional processes, leading to powerful and flexible methods for constructing
fully abstract models of programming languages, with applications in program
analysis and verification. In a broader context, we can regard game semantics
as a first step towards developing a positive theory of intensional structures
with a robust mathematical structure, and finding the right notions of
invariance for these structures.
