Just a quick bullet point list of differences from the top of my head:
- Half Life has much faster run and gun gameplay (stemming from it's quake roots no doubt), while in Black Mesa it's much slower paced
- The AI in the game is completely different, Black Mesa's soldiers feel way more aggressive, again encouraging a slower pace of play compared to the original
- Lots of levels have small changes - some are cool, others kinda feel like they're just different for the sake of being different
- Xen itself is completely different; Unpopular opinion, I liked the original! It feels otherwordly and alien and oppressive, the new one is certainly pretty but lacks that atmosphere, imo
Black Mesa is a great game, one thing I have nothing but praise for is it's presentation - it's really nice to look at and they did a bang up job with the graphics and animations. But which is better is a matter of opinion, and personally I much prefer how HL1 actually feels to play.
A couple to add, with my own biases included because I love Black Mesa
- Joel Nielsen's great sound track / sound design work in Black Mesa ... I believe he admitted in an interview that some of the "squelching" sounds are recorded by slapping someone's arse O_o
- The reworked Gonarch fight is, hands down, one of the most entertaining and intense boss fights for me in recent memory. It's way better than the original for sure, which I remember just being frustrating (lack of ammo).
> Xen itself is completely different; Unpopular opinion, I liked the original! It feels otherwordly and alien and oppressive, the new one is certainly pretty but lacks that atmosphere, imo
I see both takes. Like, in the original game I actually liked Xen (except Gonarch). It felt otherwordly and empty, as if one of the reasons for earth being invaded was because there was nothing left. But BM Xen is literally another world. I prefer BM Xen, but I did enjoy the original at the time.
For a deeper look into Black Mesa / Half-Life and some of the changes, Soup Emporium did a great video here, where he only stole some of the points he raises https://www.youtube.com/watch?v=-d8KAq78gco
Other people have already given great answers: it plays faster, the levels are different, etc.
But to me the main problem of "remake replaces the original" approach is that it's a a very "content-consuming"-way to look at media. Videogames are art in their own way, old games can still be enjoyed for what they are and for what they were - same thing with movies. Silent Hill 2 (2024) doesn't replace the original Silent Hill 2. RoboCop (2014) doesn't make RoboCop (1987) obsolete.
That's my take on re_makes_, at least. With re_masters_ I'd be much more willing to recommend them over the originals (although the preservationist in me would still like the originals to be available in some way)
The game mechanics and how the story is told is worth experiencing by itself in it’s original form before seeing the modern interpretation in Black Mesa
