This version of Alien Syndrome is another variation of the original arcade release by Sega. This specific set, labeled 'set 4', represents a different revision or regional release of the game. The unprotected nature of the game suggests that this might be a later release, lacking the copy protection schemes of earlier versions. The core gameplay remains consistent with other versions – a fast-paced rail shooter focused on combat against alien creatures.  Sega's development and publication are again credited, but this revision showcases the varied iterations of the same game across different arcade locations.

Alien Syndrome (set 4, System 16B, unprotected)

Alien Syndrome (set 1, Japan, old, System 16A, FD1089A 317-0033)