HTML5 games are predominantly played in the web browser and are compatible with a wide range of devices, from desktop computers to smartphones and tablets.
HTML5 (as the term is most commonly used) encompases modern web standards (HTML 5 markup, CSS 3 and Javascript) to create complex multimedia applications. An HTML5 game allows play directly in a modern web browser without the need for third party plugins. So it has now replaced the discontinued Flash and Unity web players, as the preferred technology used to make browser games.
Although they have the advantage of providing the ability to play on mobile devices in the browser, HTML5 games have some significant downsides when compared to browser games created with older plugin based technologies, such as Flash.
Most of these issues arise from the fragmented nature of the various web browsers used to play. Many of these browser related issues can now be overcome by using tried, tested and actively maintained libraries and engines to make HTML5 games.
Some of the main issues are:
Computers with an outdated browser installed may not be able to play HTML5 games. A modern compatible browser that supports all the features the game needs has to be installed in order to play.
This can prove especially problematic in situations such as where older PCs are used to play HTML5 games, e.g. in corporate environments where they have outdate operating systems and browser software installed with no way to upgrade.