A Complete Guide to Mastering the Game Spin slots, also known as slot machines, are among the most played games in casinos and online gaming envirogaming app downloadnments. The basic idea behind these games is simple: players spin the reels, insert money, and hope to land winning symbol combinations. Spin slots are appealing because they are easy to use & have the potential to pay out large sums of money, which for some players could change their lives.