One of R.O.B.’s two compatible games, Stack-Up puts the player in control of Professor Hector, directing R.O.B. with on-screen commands. They are tasked with matching the color or the size of the on-screen block stacks, either with direct control or a programmed sequence. The game was the inspiration for one of R.O.B.’s karts in Mario Kart DS, the ROB-BLS. The name comes from Stack-Up’s product ID, HVC-BLS.