I noticed in Sonic wiki and Sonic subreddit that the game only requires a minimum of Pentium 4 1.6GHz CPU and 32 MB of VRAM with shader model 3.0 to run. Are these old requirements or did it change later on?
Topic on Talk:Sonic Mania
About system requirements
I don't think the requirements even changed. The developers probably simply replaced the recommended requirements with the minimum one. (at least I assume.) Game runs fine with a weak Pentium Dual Core (which is definitely weaker than a Core 2 Duo.) and Intel GMA 4500M. (with 64 MB of VRAM) I'm not going to change the system requirements though. I'll simply leave it the way it is.
Because system requirements are so all over the place (many games can, in fact, be played with less powerful hardware than the supposed 'minimum' one), PCGW has opted to merely list the official system requirements provided by the developer.
And so that's what we do :)
Listing the official system requirements is definitely better. If you want to see how your rig (CPU or GPU) runs the game, you can search it on YouTube to see how it performs during the game. Trying the demo version of the game is a thing too.