Hi, the prg file is the same we released for the contest. It should work on a regular C64, but since Rogue4k uses all sorts of unsafe memory areas (below address $0400) I am guessing that the RR-Net transfer might interfere with the code for Rogue4k. Sorry about that.
I have uploaded an updated version of the game (rogue4k_v8.prg) that is tape-loadable, and should work for you. I would love to get some feedback if it works or not, since I have no way to test with RR-Net. :-)