The OverSim simulator was a popular choice to simulate peer to peer networks, however it was not updated since 2012. Installing it using recent versions of OMNeT++ and INET was impossible. We have spent a bit time to save the ageing model and update the OverSim codebase, so it is now possible to use it with OMNeT++ 5.4.1 or later and INET 3.6.5 (note that it is not compatible with INET 4.x versions). The model itself is functionally the same as the last public version (20121206) of OverSim.
If you need a peer to peer network simulator, go and get it from the repository we have created for the project on GitHub:
The OMNeT++ Team