"key minds" to coordinate the Flood; these include the apex of Flood evolution, known as "Graveminds". The Flood was added early in Bungie's development of the 2001 video game Halo: Combat Evolved, before the game had made its jump from the Macintosh platform to the Xbox. A design for one Flood form appeared as early as 1997. Commenting upon the inception of the Flood, Bungie staff member Chris Butcher noted that "the idea behind the Flood as the forgotten peril that ended a galaxy-spanning empire is a pretty fundamental tenet of good sci-fi. Yeah, and bad sci-fi too." Another inspiration was Christopher Rowley's The Vang series. Early design for the Flood was done by Bungie artist and writer Robert McLees, who considers himself "the architect" of the Flood; the Flood's roots are reflected in concept art of a "fungal zombie" that McLees did for the earlier Bungie game Marathon 2: Durandal. McLees also did all the early concept art for the Flood. Based on the behavior of viruses and certain bacteria, the Flood was intended to be "disgusting and nasty"; McLees modeled one Flood form off the memory of his cousin's infected thumb. The creatures were constructed from the corpses and bodies of former combatants, so the artists had to make sure the Flood soldiers were recognizable while changing their silhouette enough to differentiate them from the uninfected. Many concepts and ideas were discarded due to time constraints—initially, the Flood was intended to convert any species of the alien Covenant into soldiers. "We didn't have the resources to make it happen," McLees recalled, so they modified the game's fiction to suggest that some Covenant were too small or too frail to serve as combat troops. The technical inability to create different Flood forms procedurally informed the game's fiction that the Flood had optimized their host forms over years of trial and error, creating standardized templates that the developers used to obfuscate the repeated use of similar models. Likewise, the Flood enemy intelligence was intended to be as complicated as that of the other enemy faction in the game, but full implementation was cut for time. The dinosaur-like terrestrial wildlife that originally dwelled in Halo's environments were dropped due to gameplay constraints and fear that their presence would reduce the surprise and impact of the Flood. Bungie decided a new visual language for the Flood was needed for Halo 3. The