Crysis is a series of first-person shooter video games developed by the German company Crytek. The main characters of the game are military protagonists equipped with advanced powered armor called nanosuits, which provide them with various special abilities through dedicated "modes". The augmented strength mode allows the user to be almost superhumanly strong; the defense mode enhances the suit's ability to withstand bullet and shrapnel impacts; the speed mode increases the character's movement speed to the point of being able to run and jump cars; and the cloaking mode allows the user to become virtually invisible.

The player controls the superhero-like protagonists through the CryEngine 3 game engine, which provides real-time 3D rendering and virtual world generation capabilities. This game engine was used in the first Crysis, as well as its two sequels. It was also used in the recently released remastered version of the original Crysis, and it is set to be featured in the upcoming third installment of the game series.

The Crysis game engine and editor are based on the open source framework C++, which provides the basis for the creation of the game tools. The initial release of the CryEngine (and Sandbox) was a monolithic project with a single, basic level editor and a few other tools. Later, the developers opted for using Qt, one of the most popular open source frameworks for C++ GUI development. This allowed them to use the existing MFC-based tools while at the same time developing a modern and multiplatform GUI that is easier to maintain than the older one.