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.
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)
Note: just got past the Tentacle boss
Visually, the mod looks outstanding, prop design and art are top notch though there are some oddities (like the lowres stuff on the tram's ceiling in Inbound, and some textures) but otherwise the team did a good job. Levels are excellent too, filled with various levels of detail.
Audio wise, there are some problems (music overpowering voices/gunshots/etc.) but it's good overall; the Magnum feels satisfying to use. Voice acting's also good but it was odd to see Eli Vance (and other fellow African American scientists) with a 'white guy voice'. The soundtrack is excellent but as mentioned before, occasionally overpowers the in game sound.
Gameplay: This is the best (and worst) part of Black Mesa. It's basically just Half Life 1 but with Source graphics. Sure, there are some minor differences (mostly story related, you can use the zoom in feature with the revolver, etc.) but generally it's a close 1:1 match to HL1. So, your enjoyment level is strictly based on whether or not you love Half Life 1. If you loved it (or if you never played HL1) you'll appreciate the 8 years spent on the project. If you're like me and didn't really enjoy HL1 in its initial 1998 release (or you just got tired of it after finishing), you'll won't like it as much
Misc: The game suffers some stability/performance issues, which is unfortunate. Crashed several times (mostly death related) and the FPS can really drop in open areas. I'll attribute those problems to the Source 2007 engine though, since it's extremely outdated and unstable for detail oriented TC mods. I ran this mod on a i7 ivybridge clocked at 3.2 GHz with an AMD 7970.
In conclusion, this mod is worth a download to see how much work the team did. They really did a good job. However, don't expect too much on the gameplay side. In the end, after all the hype, it's Half Life 1 on Source and for some players who've been waiting for 8 years, that's a disappointment.
Pros: Level design is jaw-droppingly good, misc models are amazing, textures are detailed, and flows very well with one another. How the team was able to expand the game and bring it into the 21st century was unbelievable. True craftsmenship.
Cons: Animations were average (some of the weapon animations were just outright bad), the sound effects sounded public domain/just bad and inappropriate at some points (the RC was extremely dull and not convincing at all), voice acting seemed forced at times, but was decent at others.
Overall: It's a good mod, but the little things drag it down into D+ territory.
The mapping and general design is amazing. I gave it a 7 out of 10 simply because some places are extremely unoptimized and go into single digits even though I have a GTX 550 TI super clocked and a 3.6 ghz processor. The main thing that bothered me was the quality of particle effects. But they bothered me because so much more could have been put into them, though I'm overly picky about them because all I do, every day is make particle effects and other VFX for mods and indies. Other than particles and laggy places at times, This is a must have, and absolutely fantastic.