Regardless for a game like Rimworld I expect a large number of people will buy the game wanting to play on integrated graphics (Not to mention intel supposed dedicated gpu if it comes out). This effects not just old CPUs but the latest ones too.
If the game will not support intel iGPUs then the requirements on the store pages should really be updated to reflect this.
If the game will not support intel iGPUs then the requirements on the store pages should really be updated to reflect this.