10 years is not that long ago, it's 2016!
They have Radeon HD 6xxx series, circa 2011. OpenGL 4.5 certified, which is basically the latest ignoring 4.6 which is just 4.5 but with some Vulkan features shittily backported.
I had Intel Graphics 4400 (Haswell refresh) circa 2014. And also NoVideo Gayforce 820m, 2013. Both ran the Unity game just fine. Well, just barely, but 60 FPS (capped, never tried vsync off). I would consider 24 FPS playable, so that's a win for sure.
Besides, some devices still sold today which may run Unity RimWorld at least with enough fuckery (like ARM Chromebooks) only have GL 4.5, with the oldest chip designs themselves being exactly from 10 years ago.