Game rendering for this early generation of FPS were already from the first-person perspective and with the need to shoot things, however they were mostly made up using vector graphics.
Instead, they used ray casting 2.5D techniques to create a seemingly 3D environment from a 2D map, and flat sprites to draw enemies instead of 3D models.
Hovertank 3D, from id Software, was the first to use this technique in 1990, but was still not using textures, a capability which was added shortly after on Catacomb 3D (1991), then with the Wolfenstein 3D engine which was later used for several other games.
It did not apply textures to the floor and ceiling, and the ray casting restricted walls to a fixed height, and levels were all on the same plane.
FromSoftware released King's Field, a full polygon free roaming first-person real-time action title for the Sony PlayStation in December 1994.
Sega's 32X release Metal Head was a first-person shooter mecha simulation game that used fully texture-mapped, 3D polygonal graphics.
[5] A year prior, Exact released the Sharp X68000 computer game Geograph Seal, a fully 3D polygonal first-person shooter that employed platform game mechanics and had most of the action take place in free-roaming outdoor environments rather than the corridor labyrinths of Wolfenstein 3D.
The following year, Exact released its successor for the PlayStation console, Jumping Flash!, which used the same game engine but adapted it to place more emphasis on the platforming rather than the shooting.
Static lightmaps and 3D light sources were also "baked" at render time and added to the BSP files storing the levels.
Probably the biggest reason for its popularity was that the engine architecture and the inclusion of a scripting language made it easy to mod it.
[15] id Tech 3, first used for Quake III Arena, improved from its predecessor by allowing to store much more complex and smoother animations.
The next-generation GeForce 3 or Radeon 8500 were recommended due to their more efficient architecture, though their DirectX 8.0 vertex and pixel shaders were of little use.
A handful of games still supported DirectX 6.0 chipsets such as RIVA TNT2 and Rage 128, and software rendering (with an integrated Intel GMA), though this was apparent that even a powerful CPU could not compensate for the lack of hardware T&L.
The new generation of graphics chips allowed pixel shader-based textures, bump mapping, and lighting and shadowing technologies to become common.
AA and AF had been supported by many earlier graphics chips prior to this but carried a heavy performance hit and so most gamers opted not to enable these features.
With these new technologies game engines featured seamlessly integrated indoor/outdoor environments, used shaders for more realistic animations (characters, water, weather effects, etc.
This was later rectified to work with vast outdoor spaces, with the introduction of MegaTexture technology in the id Tech 4 engine.
This new engine was notable in that, among other things, it had very realistic facial animations for NPCs, including what was described as an impressive lip-syncing technology.
These engines include realistic shader-based materials with predefined physics, environments with procedural and vertex shader-based objects (vegetation, debris, human-made objects such as books or tools), procedural animation, cinematographic effects (depth of field, motion blur, etc.
Preliminary information about this engine which was still in early phases of development tended to show that id Software was looking toward a direction where ray tracing and classic raster graphics would be mixed.