I'm looking at a game which gives 'Intel HD Graphics 4000' as one of its requirements. My Macbook Pro Retina mid-2014 has 'Intel Iris 1536 MB'; will that be OK?
There are 3 types of mid 2014, two with integrated graphics & one with a discrete card.
The integrated chip is Intel 5100 or 5200 so yes, well within spec, even if you don't have the dual-graphics version with a GeForce GT 750M.
Yes, the Iris Pro should be enough for the game. The HD 4000 is included in the Mid-2012 MacBook Pro so yours is newer than it, so definitely will work.
Yeah, your GPU's light years ahead of the HD 4000.
No, it won’t work. Iris by itself gives only video memory of 128MB. Iris is basically more for graphic not gaming. You need iris and Nvidia video card together to get the best performance.