They aren't making anything different, just in greater detail.

However, I had a remake of Damnation planned, but could never really get into it other than the basic 3d layout. I couldn't get a good theme to work for it that would account for the layout's oddities (the horizontal beams leading to the sniper ridge, the double-backing setup of the upper base, etc.) so I'm not bothering with it for a while. Once I can competently model terrain, I will, however, make a Chill Out remake which will have a very concise and logical (if you can call Forerunner architecture logical) theme.