if u have .nrg format (iso) u can convert it into .iso format with free programs like imageburn. The iso image format is more simple to open than the .nrg .
PS: There is already a tool that extract almost everything from this game. Anyway if u are interested only in the 3d models of the characters there is already a pack with the models on the web in obj format on the web.
PS: There is already a tool that extract almost everything from this game. Anyway if u are interested only in the 3d models of the characters there is already a pack with the models on the web in obj format on the web.