All game engines use rasterization.

Rasterization was created long ago to project 3D triangles to 2D so hardware blitters on VGA cards could render triangles much faster. But rasterization requires a lot of processing steps and is fiddly.

Ray tracing is simpler but slow

Ray tracing has also been around a long time. 3D scenes are rendered in a clean mathematical way that's modeled after real world lighting. Ray tracing can render a 3D scene directly to the framebuffer without flattening triangles to 2D. In spite of these advantages, ray tracing is not used for games because even with hardware acceleration, traditional ray tracing is too slow to render entire scenes at good frame rates.

New ray tracing method needed

Raylogic worked for years to create a version of ray tracing specifically for games. A deterministic ray tracing algorithm was developed to render entire scenes, not just lighting. It provides fast, real-time ray tracing for 3D scenes. Triangles are rendered directly from the scene to the framebuffer without projection. All rendering is done with compute shaders inside Vulkan. No other part of Vulkan is used.

Rasterization replaced

Removing rasterization is monumental. It eleminates draw calls, frustum culling, near/far clip planes, occlusion culling, overdraw reduction, vertex/pixel processing, screen space projection, environment/cube mapping, lightmap baking, forward/deferred rendering, level of detail meshes, transparency ordering, shadow mapping, depth buffers, texture filters and more.

Fully ray traced engine

Rayve is a fully ray traced engine, meaning the engine's entire render pipeline is implemented with ray tracing. Please note that Rayve uses a proprietary, deterministic form of ray tracing, not traditional ray tracing.