GPU based realtime engine for the viewport implemented for Blender version 2.8, using Industry standard PBR (Physically Based Rendering).
Eevee engine will be a PBR realtime engine for Blender 2.8 viewport aimed at replacing the blender internal render engine.
From the Eevee Roadmap
Eevee will follow the (game) industry PBR (Physically Based Rendering) trend, supporting high-end graphics coupled with a responsive realtime viewport.
Some of the main features:
Support for all realistic Blender light types
Soft Shadows
PBR materials with Ubershaders similar to those used in game engines
Image Based Lighting
Glossy Rough Shaders
Diffuse approximation
Post Process Effects like Motion Blur, Bloom, Tone Map, Depth of Field, Ground Truth Ambient Occlusion
Probe Objects
Environmental Map Arrays
More info on https://wiki.blender.org/index.php/Dev:2.8/Source/Viewport/Eevee