In a move most people would find confusing at least, and odd and frustrating at most, modder Itszu has created a CS: GO custom map modelled after the iconic halo level Blood Gulch. Painstakingly reproduced the map has only a few changes here and there to still be playable in CS:GO, like bomb sites and buy zones. Other than that the Halo: CE fan favorite is completely recreated. Itszu tells us on his steam works page
“All level geometry is hand-done, including brushwork and displacements. Textures have been modified as needed to support Source’s unique texture parameters. All scenery (rocks, trees) ported with Wall Worm Model Tools from Gearbox’s level assets for Halo: Custom Edition, with hand-done custom collisions to conform to Source’s convex requirements. Some textures are heavily modified from the original, and others are entirely new due to differences in texture tech between halo’s Blam engine and Source 2013.”
If you want to pick up the mod go check out the Steam works page, its playable in custom games of CS:GO.