Is it playable to the end?

yes

Should still work on XP. Also SmartSteamEmu still works with the game

OK. I played it a long ago and when I tried to continue, the game complained that older savegames couldn't be used with new version.

I didn't want to play it again from the start to find that the game is unfinishable.

OK, I've finished Black Mesa (again). It turned a bit strange, but it deserves the price tag.

The strange bit is Xen. If you played Half-Life, you'll feel comfortable with Black Mesa levels. Although some events have been changed and you must travel through new paths, the main events (i.e: the accident, your way to the surface, testing the engine in Silo D...) are the same, and the facilities are the same as in Half-Life.

But everything changes when you get to Xen. They have redone everything, and it seems that the only thing they've used from the old levels are the chapter titles. That's not bad (Xen levels in Half-Life were... meh), but that depart from canon is strange. Gonarch Lair is the best example... as far as I remember, in Half-Life it was only a platform level with a boss fight (Gonarch), but in Black Mesa is a sucession of showdowns with Gonarch until the end of chapter (when you kill Gonarch in a furious fight).

So the first part (Black Mesa) is a proper remake (forget about Half-Life: Source... it shouldn't be on stores), but the second part (Xen) is a new game.

Some things that they should improve (and people playing should be aware):
- BUG: The long jump is different from Half-Life. In Half-Life you needed to crouch and then jump to do a long jump, in Black Mesa you must do a double-jump (pressing twice the jump key). I feel more intuitive this way, but the bug is that the game prompts you to do CTRL+Space.
- The tentacles on Blast Pit are harder than in Half-Life. In Half-Life was easy to taunt them with a grenade and do a run while they're distracted... in Black Mesa they react faster to your noise, and even hear you when walking crouched.
- The last fight with Gonarch is VERY hard. Although is short (I used the word furious before), is even harder than kill the Nihilant.
- BUG: In the ending cutscene, there are no subtitles for the g-man speech.
- BUG: When you started Half-Life, there were some captions about Gordon Freeman. Also, when you died in some ways (i.e.: jumping into the teleport before being ready) a report (like those in endgame) was shown. Both captions and reports (except the one after finishing the game) are missing.

I'm glad I wasn't the only one to note how much more difficult the Tentacles creature in the blast rocket chamber is! I thought I was loosing my mind because on the original, I could just toss a grenade and keep to the sides while crouched to keep them distracted. What I had to do in this was basically toss a grenade and then start running to the ladders and toss another just before climbing up and repeat. If I crouched they could still "hear" me, kill me quickly before I could react. So yeah...opposite thinking required to how it use to be. I was talking to a co-worker who is a huge half life fan and he said I was crazy and that the way I ended up doing it is how it should be done?

And it has been so long since I played the original to the end, but I didn't immediately know what was different in Xen. But what I do KNOW is that XEN is literally half the game now and not just the last 1/4 of it. Black Mesa might very well be the longest FPS game I've played with a linear story and path to take.

I also ran into a few places where I was able to glitch through the wall in parts I wasn't supposed to yet in Xen. A few places with the leaves you have to 'awaken' to get them to drop etc. I was able to squeeze through but then found that the scripting needed to actually make things progress wasn't getting triggered doing this.

And the final boss was crazy. I actually was able to take out Gonarch on the final section quite easily. I found he wouldn't go around the rock near where you first drop down. So I stayed behind it...just took the hits from his babies and just tossed det packs under him then grenades. Finally a few strafes back and forth from behind the rock to him with the shotgut to take him out. But the final boss I used up like every bit of ammo I had down to like 2 shot gun shells and the alien arm cannon thing. (Never can remember what it is called...) and it took FOREVER to kill him.

But for the asking price and especially for the Christmas Eve sale price I got it for off steam @ 15.99 during that sale, it is very much worth the price of admission!