It’s based on the Xbox 360/PS3 console port of the game. People figured this out pretty quickly, because a VTOL flying mission that these consoles couldn’t handle was missing from the remaster as well (later added back in with a patch). Colors are oversaturated, texture, object and lighting quality are down- or sidegraded (many not worse on a purely technical level, but different without being better for no reason, as if the outsourced Russian devs had a quota of changed assets to fill), lots of smaller and larger physics interactions are gone, because they were never part of that old console port. AI (quite a bit selling factor on the original as well, on top of the graphics and physics) is simplified as well. The added sprinkles of ray-tracing features here and there, as well as some nicer water physics do not make up for the many visual and gameplay deficiencies. On top of that, there are game-breaking glitches that weren’t part of the original.

The biggest overall problem I have with it is that it just doesn’t look and feel like Crysis anymore and instead has the look of a generic tropical Unity Engine survival game. The original had a very distinct visual identity, a muted, realistic look, but with enough intentional artistic flourishes that made it more than just a groundbreaking attempt at photorealism. You can clearly see this if you compare the original hilltop sunrise to the remaster. Crysis also had an almost future-milsim-like approach to its gameplay that is now a shell of its former self.

I will admit that to the casual player, many of these differences are minor to unnoticeable. If you haven’t spent far too much time with the original, you’re unlikely to notice the vast majority of it and might just notice how ridiculously saturated everything looks.

At the very least you can still buy the original on PC. On gog, it’s easy to find, but on Steam, it’s hidden for some reason [insert speculation as to why here]: If you use Steam’s search function, only the remaster appears. You have to go to the store page of the stand-alone add-on Crysis Warhead (the only Crysis game that did not receive the remaster treatment, likely because it was never ported to console), which can be purchased in a bundle with the original as the Maximum Edition (this edition also does not appear in the search results): https://store.steampowered.com/sub/987/