This is the discrete event simulator I wrote for the EPSRC project OPSnet. It's written in C++ because it relies on the C++ STL.
Note that the simulator uses the Mersenne twister random generator by default. This is implemented in the C++ header file MersenneTwister.h
To use this simulator, you'll need the Simulation::Automate module from CPAN.
After installing this module. you just create a .data file with your DOE description, and run it using the synsim script:
./synsim -i yourfile.data

Try ./synsim -h for help on the flags, and read the Simulation::Automate docs if you need to know more.
Read TEMPLATES/opsmodule8.templ and SOURCES/opsmodule8.cc for more info on the OPSnet simulator.