Stack-Up is an NES video game. It was one of the two video games to use R.O.B., a "toy" robot that was included with the NES system in order to increase sales and distance the system from the failing video game systems of the time.
There were three main game modes: Bingo, Direct, and Memory. All three games have player one play as Professor Hector. In Direct, you must jump on large switches to direct R.O.B. to stack up the blocks in a certain order in the fewest moves and least time. The player is supposed to press start as soon as the blocks are in the correct order, and the level will be beaten, moving on the next level. Memory is similar to direct, except you must set up a "Program" for the R.O.B., and then run it when you are finished. Bingo requires the player to make a row or column of five "active" switches, which will activate a movement. The goal is to stack the blocks in a particular order, while trying to prevent Flipper from causing undesired actions and avoiding Spike, who will knock the player off the board. There is also a two player mode of Bingo, where a second player can use the second controller to play as Professor Vector. In two player mode, the players compete to move as many blocks to one of their trays as possible.
The R.O.B. has become somewhat of a representative of the NES as a system, with major appearances in games such as Super Smash Bros. Brawl and Super Smash Bros. For Nintendo 3DS/Wii U, as well as cameos in F-Zero, Pikmin 2, and Kirby's Dream Land 3. Professor Hector has also made some cameos and minor appearances in other games, such as in Tetris DS and Kirby's Dream Land 3. The "Blocks" that were used in the game as accessories for R.O.B. also later appeared as treasures in Pikmin 2, where they are known as the Fond Gyro Block, Memorable Gyro Block, Lost Gyro Block, Favorite Gyro Block, and the Treasured Gyro Block, along with a broken R.O.B. head which is called the Remembered Old Buddy, a reference to its actual name, the "Robotic Operating Buddy". This game was later given somewhat of a sequel with Gyromite, another Robot Series game where you play as Professor Hector.
This game is the first appearance of both Professors, and the only appearance of Spike and Flipper.
While the game was released before Gyromite, this game is extremely rare, most likely because the game was not seen as very desirable by consumers, and that Gyromite was a pack-in game.