I partially disagree, GI is easy to do most of the time with baked lighting, but reflections (especially more diffuse reflections) are hard unless you have very simple environments or tons of gpu resources to spend on rendering alternate camera angles. Even the more modern rasterized reflection techniques such as parallax corrected cubemaps or screen space reflections break easily if you look at them wrong. Raytraced global illumination and soft shadows are still great though, but are more easy to get around with regular rendering in most games where the environments are very static.
that's just part of RTX remix and somewhat the point of that tool. After all you need to get proper RTX materials in there and why not upres the assets as well while you are at it?
You have to use new assets for these old games if you really want to make the most out of ray tracing because PBR materials are necessary to better simulate the way light and reflections bounce off a surface.
I disagree that you really need to put much effort into updating the materials to get benefits from rtx. HL1 RTX looks pretty great with only the bare minimum PBR remasters, because PBR and RTX are 2 separate things that both improve a game's look. PBR materials help rtx just as much as PBR materials help regular rendering, and rtx helps PBR materials only a little bit more than rtx helps regular materials. All of the effects used in PBR materials apply the same to regular rendering as with RTX.
I might be in the minority here, but I couldn't help but think Half-Life 2 still looks really good for a game released in 2004. Obviously "RTX on" is nicer to look at, but all the small details like the magnifying glass that actually magnifies made me appreciate the old assets/graphics so much, what a milestone it was.
The cool thing about raytracing is it doesn't really matter how complex a scene is. The bad thing about raytracing is it doesn't really matter how complex a scene is.
If your card can't run remixed HL2, it also won't be able to do HL1
They sort of announced HL3 in the post credit scene on HLAlyx, but of course we've been promised HL3 before so even if we get it it'll be another 10 years probably. Alyx was so incredibly good though.