1MB cartridge.

Kirby's Adventure for NES back in the day was 768KB. Metal Slader Glory (1991 Japanese release) was a 1MB cartridge.

Most c64 games would fit in about 1/6 of a 170k floppy disc, and loaded entirely into memory at once. Really big ones were on about 4 of those discs. Well, both sides of two discs, since you could flip them over and use the back side.

This thing occupies the equivalent space of about 6 or 7 disc sides. It's crazy huge for a c64 game.

1 Megabit, which works out to be 128 kilobytes.

Huh, that's not even an entire side of a 1541 disc.

But I also just bought it and the game itself lives in a .crt file that OSX says is 1,034,272 bytes, and rounds to 1 megabyte. So I think you may be wrong in saying it is one megabit.

(Doing the math, it is about 5.9 1541 discs worth of data, possibly a bit more if you consider theoretical directory tracks and/or custom recording formats that sacrifice some data density for blazing speed. Not that there appear to be any plans for a floppy version.)