Nintendo 64DD

Nintendo 64DD is an accessory for the Nintendo 64. It is a mini-console that can be connected on the bottom of the N64. It released five Mario games and 20 other games during it's time. It didn't sell well in the market and was never released out of Japan (although some markets outside of Japan has sold the 64DD).

Trivia
The five Mario games were Mario Artist. This had a failure because it was slightly plagiarising Mario Paint on the SNES.

Nintendo discontinued it three months after the intial release. This is the second Nintendo console that was a commerical failure. The first was the Virtual Boy.

Some of the planned games were either scrapped, made as original N64 games or ported to the Gamecube.