'Donkey Kong', a 1981 video game.
Mike Mika likes to play video games with his 3-year old-daughter, with the classic Donkey Kong being one of the titles the two would play.
Ellis, Mika's daughter, enjoyed playing the game, but wished she could do so with a female protagonist.
"One of the first games I introduced her to was Super Mario Brothers 2, which was the first one where you can select your character," Mika told ABC News. "So when we back to 'Donkey Kong,' she said, 'Can I play the girl?'"
In the original game, players take the role of Mario (originally known as "Jumpman") and scale a tower of ladders and girders to save Pauline from the giant ape Donkey Kong. In Mika's hacked version, the gender roles are swapped with Mario, and not Pauline, being the one in peril.
"I told her we couldn't in that particular Mario game, she seemed really bummed out by that," Mika explains on his YouTube page. "So what else am I supposed to do? Now I'm up at midnight hacking the ROM, replacing Mario with Pauline. I'm using the 2010 NES Donkey Kong ROM. I've redrawn Mario's frames and I swapped the palettes in the ROM."
He even replaced the "M" (for Mario) at the top of the screen with a "P" (for Pauline).
Mike Mika is no stranger to the development of video games, having worked on more than 120 video games (according to website Giantbomb) since the original Game Boy.