That's the size of a game on the original NES. Some masochistic developer called morphcat decided to make a new game that would work on the original hardware. In the process, they made the rest of us look pretty lazy.
Check out the explanation of how it works:
This game looks like a modern indie, but it runs on the same hardware that gave us some very well designed and fun, yet almost certainly less visually tight. It proves that the industry of video games has evolved, but not just because we have better hardware. And it also proves that software is in a pretty sad state right now.
Just the php of my website wouldn't fit on an NES cartridge. Everything does not need to be optimized to the same extreme. But I think there's still a lesson here.