WARNING: Contains pornographic material.
Super Maruo's title screen.
Super Maruo (スーパーマルオ) is an unlicensed game released in Japan in 1986. Although very rare, this game is the first unlicensed Famicom game and the first unlicensed adult Famicom game as well. Despite the name, it has no relation to Mario at all. (with the exception of the main character being an edit of Mario from Super Mario Bros.).
The gameplay is very simple. You're a man and you have to go after the woman running around on the screen. At the same time, you have to avoid the dog that is chasing you around. After grabbing the woman, you are awarded a scene of her stripping or posing.  Later, your character and the woman also begin to lose their clothes during gameplay. If you grab the woman for the second time, the game will display an erotic animation of the woman in sexual practices. After that, you have to repeat the whole process again. There are currently four erotic animations within the game.
The game shows some strange block collisions, as the woman will continue running away from the player even if he manages to catch up with her. Perhaps, it's necessary for the player to grab her frontally in order to make his try count. Despite this, if we look closely at the movement behaviour of the woman, the player can exploit it and find a movement pattern to grab her more easily.
This game appeared in magazine scans and was sold in shops for ¥6,800 (about $87 today). The high price of the game back then likely contributed to the low sales and rarity of the game. It was rumored that Nintendo also shut down the sales of this game almost immediately after its launch. The final bid for the original cart was ¥499,000 (about $6452 dollars).
These variants of this game are known to exist: two carts with a switch and three carts without the switch. (unknown if these are official or not) It's unknown what the switch actually does but a magazine scan does show it was located in the up left part of the 'u' in "Maruo" while the original cart that was in the auction has it in the upper right of the 'u'. 
Due to rumors of its rarity (it was said that only 7 cartridges of this game were found, two of them bootlegs), a bootleg cartridge of this game was seen trying to be sold in Argentina for a price of 40,000 pesos (more than $2600 US dollars). In time, the price drop to less than 1000 pesos when it was discovered that multiple bootleg cartridges of this game were made in the 90s, and a good amount of them arrived to the country. There is rumor of a seller from that country that received by mistake 200 copies of the game. As of April of 2015, he was known to have 15 copies.
- ↑ http://murakun5555.at.webry.info/201010/article_11.html
- ↑ http://wave.ap.teacup.com/pachi/timg/middle_1280015201.jpg
- ↑ http://insertcredit.com/2007/07/16/news-super-maruo-sells-for-499000-yen-on-yahoo-auctions/
- ↑ http://wave.ap.teacup.com/pachi/timg/middle_1302245935.png
- ↑ https://www.facebook.com/764003373674981/photos/a.764024160339569.1073741828.764003373674981/835073299901321/?type=3&theater