I finally got around to (minimally) cleaning up my code from the 2006 Nanoletters paper and put it up on github (https://github.com/jarvist/Amphisbaena). This simulates coarse-grain on-lattice morphology generation of polymers via a slithering snakes / reptation model [amphisbaena], and then also enables you to carry out mobility simulations via Time of Flight (ToF), drift velocity or diffusion [gorgophone].
It’s coded in C and is rather sneaky in some ways (have a look at the oroboros data structure!