  Two different forms of responsibility, counterfactual and seeing-to-it, have
been extensively discussed in the philosophy and AI in the context of a single
agent or multiple agents acting simultaneously. Although the generalisation of
counterfactual responsibility to a setting where multiple agents act in some
order is relatively straightforward, the same cannot be said about seeing-to-it
responsibility. Two versions of seeing-to-it modality applicable to such
settings have been proposed in the literature. Neither of them perfectly
captures the intuition of responsibility. This paper proposes a definition of
seeing-to-it responsibility for such settings that amalgamate the two
modalities.
  This paper shows that the newly proposed notion of responsibility and
counterfactual responsibility are not definable through each other and studies
the responsibility gap for these two forms of responsibility. It shows that
although these two forms of responsibility are not enough to ascribe
responsibility in each possible situation, this gap does not exist if
higher-order responsibility is taken into account.
