It may surprise a lot of people to learn that Crysis Remastered isn't actually based on the original game — at least, not the original PC build.
That's not to say that Crytek cut corners on Crysis Remastered. In fact, it went out of its way to give the PC build more attention separate from the console versions. We were able to do an interview with Crytek recently, in which the developer explained that the game is meant to push the limits of PC hardware for not just this generation, but the next one as well.
However, according to John Papadopoulos of Dark Side Of Gaming, the remastered version is based on the PS3/Xbox 360 versions of the game. That doesn't change the unprecedented visual fidelity in the game, but there are some noticeable changes if you were looking for the original PC version. For example, grenades don't affect bushes as they did in the original.
Changes to environment mapping are also making some areas appear to be "flat" compared to the original PC version. This seems to be in exchange for sharper assets elsewhere — a quality for quantity exchange. The most glaring change, though, is the complete removal of the Ascension mission. In addition, if you're the kind of player who enjoyed being able to run diagonally in speed mode, you'll need to stick with the original, as you will not be able to do it in the remaster.
All of that being said, if the game holds up as well as the original — and we're pretty sure it will — it'll still be impressive 13 years from now. Remastering games has proven to be difficult as of late, so perhaps we should have mitigated our expectations. However, taking the game for what it is, it's difficult to say that it's not good. It's still Crysis, after all. It's still breaking hardware and pushing the limits of what is acceptable to dream. If you absolutely need that original experience though, there are mods that can bring you more up-to-date without sacrificing everything that you love about the original.
Source: Dark Side of Gaming