If you want to explore the Black Mesa Research Facility from a new perspective, check out Halfmapper, a renderer that lets users explore the maps of Valve's Half-Life and Counter-Strike. It also makes some pretty cool isometric shots, making Half-Life look more like a turn-based strategy game than a first-person shooter.
Halfmapper, the work of Gonzalo Ávila Alterach, is a free download for Windows PC. It enables noclip mode and won't render models, decals and other objects, allowing players to get gorgeous, distant views of Black Mesa, classic Counter-Strike maps and more.
All that's really required is an installation of Half-Life and the free to download Windows binary.
Here's what a few Counter-Strike maps — Dust, Office and Vertigo — look like in isometric view.