  Exploring the possible consequences of spatial reciprocity on the evolution
of cooperation is an intensively studied research avenue. Related works assumed
a certain interaction graph of competing players and studied how particular
topologies may influence the dynamical behavior. In this paper we apply a
numerically more demanding off-lattice population approach which could be
potentially relevant especially in microbiological environments. As expected,
results are conceptually similar to those which were obtained for lattice-type
interaction graphs, but some spectacular differences can also be revealed. On
one hand, in off-lattice populations spatial reciprocity may work more
efficiently than for a lattice-based system. On the other hand, competing
strategies may separate from each other in the continuous space concept, which
gives a chance for cooperators to survive even at relatively high temptation
values. Furthermore, the lack of strict neighborhood results in soft borders
between competing patches which jeopardizes the long term stability of
homogeneous domains. We survey the major social dilemma games based on pair
interactions of players and reveal all analogies and differences compared to
on-lattice simulations.
