Playing Black Mesa feels like meeting an old friend, only to realize that while you still like them, and that they're now easier on the eyes, they now gained a few questionable quirks through the years along with seeing some of their frustrating qualities as they truly are. Stuff like crouch-jumping are as painful as I remember them, and certain puzzles became hair-pulling because of them (that laser mine criss-crossing labyrinth). Some puzzles also got changed along the way inspired by Half-Life 2, but without the subtle tutorial to teach you that said puzzles exist, unlike how Portal or HL2 does it, leading to some situations where my nostalgia-based solution clashed with what I was supposed to do.
Still, despite parts like On A Rail getting truncated lots, the game really is as awesome as I remember it as. Just awaiting Xen so we can complete the saga, and if it looks as beautiful as a preview we see in the game looks, then I'm sure the Xen parts will be quite awesome this time round, depending on how they do it.
Also, this scene made me go
when I first encountered it: