  Crime is pervasive into modern societies, although with different levels of
diffusion across regions. Its dynamics are dependent on various socio-economic
factors that make the overall picture particularly complex. While several
theories have been proposed to account for the establishment of criminal
behaviour, from a modelling perspective organised crime and terrorist networks
received much less attention. In particular, the dynamics of recruitment into
such organisations deserve specific considerations, as recruitment is the
mechanism that makes crime and terror proliferate. We propose a framework able
to model such processes in both organised crime and terrorist networks from an
evolutionary game theoretical perspective. By means of a stylised model, we are
able to study a variety of different circumstances and factors influencing the
growth or decline of criminal organisations and terrorist networks, and observe
the convoluted interplay between agents that decide to get associated to
illicit groups, criminals that prefer to act on their own, and the rest of the
civil society.
