other video game areas. Other major trends in mobile games have include the hyper-casual game such as Flappy Bird and Crossy Road and location-based games like Pokémon Go. Mobile gaming has impacted the larger video game market by drawing demand away from handheld video game consoles; both Nintendo and Sony had seen major drops in sales of their 2011 handhelds compared to their 2004 predecessors as a result of mobile gaming. At the same time, mobile gaming introduced the concept of microconsoles, low-cost, low-powered home video game consoles that used mobile operating systems to take advantage of the wide variety of games available on these platforms. Calculator games Calculator gaming is a form of gaming in which games are played on programmable calculators, especially graphing calculators. In 1980, Casio's MG-880 pocket calculator had a built-in "Invaders" game (essentially a downscaled Space Invaders clone), released in the Summer that year. Another early example is the type-in program Darth Vader's Force Battle for the TI-59, published in BYTE in October 1980. The magazine also published a version of Hunt the Wumpus for the HP-41C. Few other games exist for the earliest of programmable calculators (including the Hewlett-Packard 9100A, one of the first scientific calculators), such as the long-popular Lunar Lander game often used as an early programming exercise. However, limited program address space and lack of easy program storage made calculator gaming a rarity even as programmables became cheap and relatively easy to obtain. It was not until the early 1990s when graphing calculators became more powerful and cheap enough to be common among high school students for use in mathematics. The new graphing calculators, with their ability to transfer files to one another and from a computer for backup, could double as game consoles. Calculators such as HP-48 and TI-82 could be programmed in proprietary programming languages such as RPL programming language or TI-BASIC directly on the calculator; programs could also be written in assembly language or (less often) C on a desktop computer and transferred to the calculator. As calculators became more powerful and memory sizes increased, games increased in complexity. By the 1990s, programmable calculators were able to run implementations by hobbyists of games such as Lemmings and Doom (Lemmings for HP-48 was released in 1993; Doom for HP-48 was created in 1995). Some games such as Dope Wars caused controversy when students played them in school. The look