Virtual LEGO / Technics / Mindstorms simulation environments
Recently I met with TeamSim. Its possibilities are impressing:


you can make own robot via LDD and export it to the program
you cam make own mat (FLL, WRO, sumo mats are already available)
you can program a robot via NXT-G


I have no chance to investigate this program in detail, but I think it's what you want.