Project X: Love Potion Disaster, or just Project X is a fan-made hentai side scrolling beat 'em up type game featuring characters from Sega's Sonic the Hedgehog series and fan characters made by Zeta Team, the leaders of said team are NeoEclipse and Zeta R-02 (also a pornographic artist).
The game was first released for free on November 20th, 2009. Despite being around for over a decade, the game is still incomplete and in-development hell, only receiving a major update once every 18-36 months. This is primarily due to the games status as a passion project, with the creators not charging players for the download or attempting subscription based payment via Patreon or SubscribeStar. Leading to most of the work getting done on the side while they have to take care of real-life issues. The ultimate goal of the creators is to have 8 major stages like most games in the series that it is based on.
The basic premise of the game is that while Dr. Eggman is attempting once again to take over the land, a pair of scientists making a love potion wind up using too much of the eponymous Element X. This results in a massive pink cloud covering the region that causes everyone including Children Plants, Feral Animals, Robots, aliens, and mythological creatures such as ghosts, mermaids, and demons; to become sex crazed zombies. This also leads to the birth of pink, crossgendered, nymphomaniacal, version of Chaos known as Venus who seeks to spread the cloud's influence and force/seduce those affected to become part of her harem of boyfriends and girlfriends.
The player's character is one of the few characters mostly unaffected by the cloud and will attempt to find a way to reverse its effects. Originally the only playable character was Zeta-R02's fan character Zeta the Echidna. But over time they would come to add other characters from the main series including Blaze the Cat, Amy Rose, Rouge the Bat, Cream the Rabbit and her sidekick Cheese the Chao, and Tails the Fox as the token male. At one point, Rockcandy's Zu was also a playable character. Conversely, most of the initial enemies were based on hostiles from the Sonic series such as the badniks, dark gaia minions, Boom Boos and Chao before shifting to more original and unique enemies.
Game-play wise its a standard side-scrolling beat 'em up, with minimal platforming and unique stage design. Each of the playable characters has different stats such as jump, speed, strength, defense, and special move power. They each have a basic combo, a dash attack, a jumping attack, a ranged special, and an area of effect special. The player must defeat all the hostiles in the area within 90 seconds before moving on to the next. Enemies have different movement patterns, health bars, and even special attacks. If they get to close, they will remove the players clothes and one of two animations will play in which the enemy rapes the player's character and they take damage. Too much damage and you'll lose a life. Health can be replenished by collecting condoms and birth control pills. There are secret areas with challenges and puzzles to potentially earn Chaos Emeralds, which will increase maximum health and power. You can also score points with combos and by rescuing other Mobians from the effects of the cloud.
There are currently 5 completed stages. Most of the sound assets including music and voice acting is ripped from existing triple a games from in and outside of the Sonic series. There are also a number of pop-culture references ranging from Sonic to Spongebob Squarepants, Street Fighter, The Little Mermaid, Ecco, Darkstalkers, and much more.
There are also additional game modes, including an Arena Mode where you fight hordes of enemies leading to a face off with evil (horny) versions of of the playable characters and then Big the Cat, Boss Rush where you fight the game's bosses back-to-back, those bosses being Decoe, Bocoe, Bokkun, a hedge of Piranha Plants, Lah the Ghost, Sonic the Werehog, Neokat's OC's, Zeena of the Deadly Six, Big the Cat and Venus.
Project X Covers a massive list of fetishes, including, Rape, tentacles, oral, fisting, vore, bestiality, cub, hyper, inflation, cumflation, worms, knotting, underwater sex, impregnation, unbirthing, pegging, tail sex, cosplay, transformation, watersports, bdsm, spanking, sex toys, gender transformation, intersex, lactation, goo, oviposition, flying sex, unorthodox penetration, gay sex, lesbian sex, straight sex, group sex, and much more.