Run. Think. Shoot. Live. Source. Black Mesa is the Half-Life 2 total conversion of the original Half-Life game. Utilizing the Source engine and its endless array of possibilities and powers, Black Mesa will throw you into the world that started the Half-Life continuum and introduced Gordon Freeman to the world as a gun-toting, bullet-dodging Ph.D. in Theoretical Physics.
This review may contain spoilers
pros: balanced and enjoyable gameplay, detailed map geometry, GIBS return, faithful to the original story, very good models, actually useful npc sidekicks at times, extensive use of newer engine version effects, atmosphere of the original was largely kept if not improved at times
cons: physics quirks (especially grenades), hardly any use of vehicles, full story not recreated despite long development time, other minor bugs and limitations that were not overcome (e.g. only able to distract tentacles, walking/sneaking won't do), minor map and/or story part omissions (not counting Xen of course)