gm_flatgrass_op4 addon

Features
[1] - Navigation Mesh
[2] - Ai Nodes
[3] - Cubemaps
[4] - HDR/LDR Support
[5] - Improved textures with $detail and $surfaceprop
[6] - 3D Skybox (From HL:S with changes)
[7] - All content in map! No Requirements

Credits
Facepunch Studios - Mapping (Original)
FlodunDX - Mapping (Remastering)