skill tree of Diablo was combined with the tiered research system of X-com to produce the required effect. The science fiction television series Babylon 5 was the inspiration behind the thruster-based space combat. The in-game universe was inspired by the exploration aspects of Freelancer and Homeworld, producing "..a top down space action RPG" similar to a simplified descendant of Escape Velocity. The game's universe was originally designed to accommodate several different races, however after several months the developers had not progressed far beyond humans. At this point it was decided to retain "..the zombified ship aspect.." and refocus on that. A plant-based race and a crystalline race were dropped from the game. The zombies' organic weapons proved difficult to define, ideas such as egg-laying and infestation from creatures entering the players' ships were considered. The developers decided to produce "zombified versions" of each human-controlled ship within the game, resulting in the final design of the zombies. The zombies' reproduction was inspired by spiders, some of which "..reproduce and have their offspring crawling all over them." The developers incorporated this, allowing zombie ships to effectively reproduce by infecting the players' craft similar to Homeworld: Cataclysm's antagonist. The spacecraft were originally created by Clifford combining shapes then drawing over the top of the resultant silhouette. Due to his lack of artistic training a lot of the designs "..looked bad at first." After repeated attempts the craft started to improve visually, resulting in a collection of ships with different areas to deploy weapons. These areas, hard points, were adjusted throughout development. It was decided that each craft should perform a specific role within each size class, additional craft were created to fill any gaps. Weapons from Babylon 5 and Star Trek were added to the game, whenever the team saw examples which were not emulated within the game they attempted to create them. The randomly generated galaxies were not originally intended. After a time the developers discovered that creating the game's world was too time-consuming. Although the creation of the procedurally generated galaxy aspect took time in itself, once it was completed it grew along with the rest of the project. Balancing the randomly generated galaxies would have proven difficult, but because S.P.A.Z. is an open-world game it allows players to choose which tasks to undertake during play. Reception Space Pirates and Zombies received both positive and mixed reviews and previews from video