The Steam page for Forbidden Solitaire warns users to uninstall it "before it's too late." The demo features bizarre elements, including an eyeball offering upgrades and a character embedding gems into their own flesh. Players can cheat by inserting gems into their hand, with gameplay mechanics resembling traditional solitaire but incorporating unique twists, such as damaging opponents with removed cards. The game's lore involves a character testing the game on a vintage '90s PC, with messages from a friend discussing its controversial history. The demo includes strategic gameplay with key cards, cursed cards, and the need for careful decision-making to succeed. The player experiences a mix of card battling and puzzle-solving, leading to a sense of competence in card games.