It's not often that Halo 3 fans get a win these days. The Halo franchise is spinning wheels in general, and most of its recent successes have very little to do with its Xbox 360 era. When Microsoft fails to provide, however, fans tend to step in, which is exactly what's happened with Counter-Strike 2's Project Misriah.
Released on November 16, Project Misriah ports a bundle of Halo 3 maps and assets into Counter-Strike 2, making it possible to play an approximation of Master Chief's third outing within Valve's hit FPS. In addition to the ported content, the mod's Spartan mode features gameplay adjustments to replicate the feeling of Halo 3, backing off from Counter-Strike's quick deaths with regenerating health and slower TTK. The ODST mode, meanwhile, adds Halo weapons but leaves the CS experience largely intact.
Halo 3 and Counter-Strike aren't the most predictable pair, as the two franchises are about as far apart in style as FPS games can be. Counter-Strike does have a history of extensive modding, though, so it might stand to reason that a Halo project of this magnitude would eventually be attempted.
The Steam listing notes some limitations...
