If you have a GOG account, you might have received an email announcing a Harvest Sale. While it’s unusual for harvest to last only 48 hours, but apart from that naming blunder, the sale is no different than many that came before it. What caught my attention was somewhat creative spot the difference puzzle that accompanied it. Specifically, as pretext to share some image processing insights.

Each identified difference presents a discount code for an exciting game. Surely, one cannot let it go to waste! Alas, years of sitting in a cave in front of a computer destroyed our eyesight; how could we possibly succeed‽ Simple!