The creature's name (the first column of a CRE file) should not contain spaces or other non-alphabetical characters (you can't use digits yet), unless put between doublequotes ("). i.e. proper names are "KillerRabbitTwo" or "Killer Rabbit 2" . The same name must be used in the CRE and TER files. The creature's name is also used as the base name of the pictures. So a KillerRabbitTwo will use the file KillerRabbitTwo.gif in the subdirectory images . Spaces will be replaced by underscores (_), and double quotes will be ignored. So "Killer Rabbit 2" will use Killer_Rabbit_2.gif . You should be able to re-use an existing name, as the images subdirectory is accessed before the default GIF files.