Mr. Robotube is the mascot of MiniVisions Inc., which is a subsidiary of Choice Provisions and is responsible for the arcade-style game Woah, Dave!. He appears as an ally in BIT.TRIP FATE, replacing Radbot.
Mr. Robotube does not appear in-person in RUNNER, and instead appears as Radbot.
In FATE, Mr. Robotube is revealed to have been piloting Radbot in the intro, where Radbot explodes, releasing Mr. Robotube. In the game proper, Mr. Robotube acts as a power-up. He alters CommanderVideo's bullet spread into a sine wave/double helix pattern that can pierce through both enemies and walls. In addition, the bullets possess an exceptionally high damage boost, the highest in the game. In GIGA, a third, straight beam is added to the middle, further increasing the coverage and accuracy. Because of these traits, Mr. Robotube is easily the most powerful power-up in the game, and the second favourite of the playerbase, behind Meat Boy, if only because of the latter's ability to destroy enemy projectiles.
Mr. Robotube appears as a figment in CommanderVideo's ethereal plane. He takes the form of a light blue square. And he, alongside Meat Boy, Junior Melchkin, and CommandgirlVideo slowly drift away as CommanderVideo sinks into the afterlife before vanishing entirely from his consciousness.
Mr. Robotube appears once more as Radbot in this game's opening and closing cinematics. This can be inferred given the game's placement between RUNNER and FATE.
Radbot reappears in Runner3, but due to its dubious timeline placement and non-canon nature, it's unknown if he's still being piloted by Robotube. Mr. Robotube himself makes a couple cameos as graffiti in some of the game's Retro Challenges.