Killtendo was a game publisher who published games that look like ones published on Nintendo systems. They were the dark side of Nintendo that gained their own identity when they published a very dark game simply called "Pokemon", which was basically Pokemon Gold version, only it had a third quest after Red was defeated, which took Gold 5 years into the future, where everything was bleak and scary. By far, the most famous game they published was one that looked like a bootleg of Donkey Kong Country 2: Diddy's Kong Quest at first glance, but was actually a new game. That game was Donkey Kong Country 2: Diddy's Rampage, a game where Diddy Kong turned evil, beat Kaptain K. Rool nearly to death, took over the Kremling Krew and became king of Krocodile Isle, resulting in Dixie and K. Rool teaming up to overthrow Diddy, travelling in grittier, darker and creepy levels, plus cursed versions of levels from DKC2. Diddy's Rampage was a big success, leading to more successful releases.
In 2016, to commemorate the 25th anniversary of Sonic the Hedgehog, they were developing Sonic Out Of The Zone, a 2D platform game that promised to be an "epic entry to the series". However, because of disagreements in ideas and inability to make the engine work in a satisfactory way, the game was cancelled, and finally, Killtendo split up. Former members of the company now work at Fusion Thunder Games. Currently, they're at work developing Sonic Peregrination.