Guilty Gear X ver 1.5 is a updated version of Guilty Gear X running on the Sammy Atomiswave arcade hardware.
It features balance changes and new moves to make it more similar to XX.
There is a common misconception that GGX v1.5 contained Justice and Kliff as playable characters. That is due to the fact that GGX v1.5 is easily confused for GGX Plus on PS2, which is a rerelease of the PS2 port of GGX, with Justice and Kliff being extra playable characters as well as a Story Mode. However, since that was made prior to XX, it did not contain the new additions featured in v1.5.