I also tried an old Dell Optiplex 3010 - i5-2400 CPU (quad core, 3.1GHz), 8GB RAM, 120GB SSD - using only the integrated GPU (Intel® HD Graphics 2000). Even with all settings as low as possible, at 1080P, I was getting frame rates in the mid-teens running around open world. Turning the render resolution down to 720P did get me to a semi-playable, mid-20's FPS. This same PC does great with a GT1030 - so the rest of the PC is fine, but this is there was

I'd be curious where the lowest "playable" Intel integrated GPU is? I have some old i7-3770 and 4770k CPU's around that I'll test on. (those are still my kids daily driver PC's).