Super Robot Wars OG Gaiden is a 2007 tactical role-playing game, and direct sequel to Super Robot Taisen: Original Generation, for the PlayStation 2. The bonus segments of Original Generations, entitled Original Generation 2.5: Unified Wisdom, was regarded as a preview for Original Generation Gaiden. The game resolves many matters left unchecked at the end of Original Generation 2.5, such as one of the main antagonist's unfinished plan and the activities of one of the enemy factions.
The same tactical gameplay from Original Generations is carried over to Original Generation Gaiden, along with the Twin Battle System and Twin Command game mechanics.
The first of two new gameplay features in Original Generation Gaiden is a card battling mini-game, entitled, Shuffler Battle Mode. Separate from the main game, this unique card game allows the player to play against the computer using trading cards representing various characters and mechs in the Original Generation games, played in the style of traditional collectible card games. The second gameplay feature is the inclusion of a Free Battle Mode, where the player is given the freedom of setting their own scenario, placing which allied or enemy characters and mechs on the field in a specific environment.