Puzzle video games make up a broad genre of video games that emphasize puzzle solving. The types of puzzles can test problem-solving skills, including logic, pattern recognition, sequence solving, spatial recognition, and word completion. Many puzzle games involve a real-time element and require quick thinking, such as Tetris (1984) and Lemmings (1991). History Puzzle video games owe their origins to brain teasers and puzzles throughout human history. The mathematical strategy game Nim, and other traditional thinking games such as Hangman and Bulls and Cows (commercialized as Mastermind), were popular targets for computer implementation. Universal Entertainment's Space Panic, released in arcades in 1980, is a precursor to later puzzle-platform games such as Apple Panic (1981), Lode Runner (1983), Door Door (1983), and Doki Doki Penguin Land (1985). Blockbuster, by Alan Griesemer and Stephen Bradshaw (Atari 8-bit, 1981), is a computerized version of the Rubik's Cube puzzle. Snark Hunt (Atari 8-bit, 1982) is a single-player game of logical deduction, a clone of the 1970s Black Box board game. Elements of Konami's tile-sliding Loco-Motion (1982) were later seen in Pipe Mania from LucasArts (1989). In Boulder Dash (1984), the goal is to collect diamonds while avoiding or exploiting rocks that fall when the dirt beneath them is removed. Chain Shot! (1985) introduced removing groups of the same color tiles on a grid, causing the remaining tiles to fall into the gap. Uncle Henry's Nuclear Waste Dump (1986) involves dropping items into a pit, but the goal is to keep the same color tiles from touching. Tetris revolutionized and popularized the puzzle game genre. The game was created by Soviet game designer Alexey Pajitnov in 1984. Pajitnov was inspired by a traditional puzzle game named Pentominos in which players arrange blocks into lines without any gaps. The game was released by Spectrum Holobyte for MS-DOS in 1987 and Atari Games in arcades in 1988, and sold 30 million copies for Game Boy. In Lemmings (1991), a series of creatures walk into deadly situations, and a player assigns jobs to specific lemmings to guide the swarm to a safe destination. The 1994 MS-DOS game Shariki, by Eugene Alemzhin, introduced the mechanic of swapping adjacent elements to tile matching games. It was little known at the time, but later had a major influence on the genre. Interest in Mahjong video games from Japan began to grow in 1994. When Minesweeper was released with Windows 95, players