"That's the best price you'll see for the prequel to Metal Gear Solid V: The Phantom Pain as you're likely to see in the next six months," is what I said in November. WRONG! The latest sale sees Metal Gear Solid: Ground Zeroes reduced again to £7.19. The retail version is still around £15, that's how hot this deal is. Note: You need a PS+subscription to get this discount price (a still cheap £7.99 without), but if you have a PS4, you probably already do.
Ground Zeroes has some excellent replay value beyond the initial short run through the story as there's loads to discover around the base. Don't forget, a recent patch has added the previous platform exclusive Raiden and MGS1-style missions to each version. Check out Jon's review if you're still on the fence.