early 2000s with its Xbox line, fearing that Sony's PlayStation positioned as a game console and entertainment device, would displace personal computers. While Sony and Microsoft continued to develop the hardware of comparable top-end console features, Nintendo opted to focus on innovative gameplay. Nintendo developed the Wii with motion-sensing controls, which helped to draw in non-traditional players and helped to resecure Nintendo's position in the industry; Nintendo followed this same model in the release of the Nintendo Switch. From the 2000s and into the 2010s, the industry has seen a shift of demographics as mobile gaming on smartphones and tablets displaced handheld consoles, and casual gaming became an increasing larger sector of the market, as well as a growth in the number of players from China and other areas not traditionally tied to the industry. To take advantage of these shifts, traditional revenue models were supplanted with ongoing revenue stream models such as free-to-play, freemium, and subscription-based games. As triple-A video game production became more costly and risk-averse, opportunities for more experimental and innovative independent game development grew over the 2000s and 2010s, aided by the popularity of mobile and casual gaming and the ease of digital distribution. Hardware and software technology continued to drive improvement in video games, with support for high-definition video at high framerates and for virtual and augmented reality-based games. Early history (1948–1970) As early as 1950, computer scientists were using electronic machines to construct relatively simple game systems, such as Bertie the Brain in 1950 to play tic tac toe, or Nimrod in 1951 for playing Nim. These systems used either electronic light displays and mainly as demonstration systems at large exhibitions to showcase the power of computers at the time. Another early demonstration was Tennis for Two, a game created by William Higinbotham at Brookhaven National Laboratory in 1958 for three-day exhibition, using an analog computer and an oscilloscope for a display. Spacewar! is considered one of the first recognized video games that enjoyed wider distribution behind a single exhibition system. Developed in 1961 for the PDP-1 mainframe computer at MIT, it allowed two players to simulate a space combat fight on the PDP-1's relatively simplistic monitor. The game's source code was shared with other institutions with a PDP-1 across the country as the MIT students themselves moved about, allowing the game to gain popularity. 1970s Mainframe computer games In the 1960s, a number