What old-school 3D game recently sold for $1.5 million?

We all remember it — that game cartridge that we bought with our hard-earned allowance, only to let it go at a garage sale a few years later for a few measly dollars. And today it's worth hundreds of dollars.

Well, this game makes that one look like a piece of trash. This old-school game, which was groundbreaking in its time, recently had an unsealed copy sell for upwards of $1.5 million (yes, MILLION).

Which game do you think it was? And if you have a copy ... sell it!