Remember Mike Mika, the man who modded Donkey Kong so his daughter could play as Pauline rescuing Mario? Well, prior to that, Mika snuck a marriage proposal into a Game Boy Colour port of the Atari puzzler Klax.
Unlike the Donkey Kong mod, this was a commercial product. Hilariously, it took Mika's then girlfriend years to uncover it.
Mika recalled his story in a video interview with Wired. "She loves puzzle games, I'm doing a puzzle game now, so let me just put that out there and she will find this thing in the game," he said of his thought process at the time.
"I leave the Game Boy out, I urge her to play it, and she never picks it up," he laughed. "This goes on for literally, I think, almost like years now. It was like three years." [Editor's note: Originally I misheard the video and thought Mika said "eight years now," when upon relistening to it for the umpteenth time, it became clear that he said "like years now."]
"So do I propose to her normal, or I have this thing here that's really cool, but I can't get her to play it, ever?"
Mika explained that one day Tips & Tricks magazine called and asked if he had any special codes that had never been revealed to the public. And boy did he ever! Tips & Tricks published the piece, specifically calling Mika's girlfriend out by name and telling her what code to put into the game.
"I left that out one night with the magazine and the game, everything queued up, and I can't really be here or she'll tell me to do it, so I get out of the house," Mika said. "I just kinda drove around a little bit and she came home, checked it out, and it was a proposal.... she calls me up on the phone - like with 'yes!' The rest is kinda history after that."
Personally, I would have gone for hiding in the closet so I could be around to witness the momentous occasion, but it's hard to argue with Mika's dedication. Amazingly, this wasn't the only hidden content Mika snuck into Klax. He noted that he also tossed in a a Snake-like mini-game as well as a little adventure game in the European version. "It's almost like this little Zelda," he joked.