QUB3D is an arcade game in GTA IV.
The goal of the game is to match up coloured blocks into four pairs before they fill up the box. You have to beat the high score to win. Beating the high score earns the PS3 Trophy and Xbox 360 achivement King of QUB3D. You must complete this for 100% completion.
You can play this arcade-style game in the Modo Clothing store in North Holland, the Homebrew Cafe in Dukes, and in The Triangle Club in the Northern Gardens in Bohan. There is also a QUB3D game in a back room in Perestroika in Broker.