Random trivia time, the largest NES game ever released was Metal Slader Glory, which was a whopping -- for the time -- 8 megabits. That is, one megabyte. (A round powers-of-ten megabyte, not a computer powers-of-two megabyte, or "mebibyte" as no one would actually call it.)

For context, I reloaded this page and logged it in my browser's developer console. Just showing these comments involved the transfer of 3.06 megabytes (real powers of two ones, at that) or slightly more than triple the size of that entire cartridge. Just to display some kibitzing on the internet.

Most NES games were significantly smaller. The maximum the NES can address within ROM without mapper chips IIRC is 49120 bytes, and many of the initial launch titles, not to mention Super Mario Bros. 1, didn't even fill that whole space.