One of my prized possessions in the '60's was a space invaders game that ran
fast and was a lot of fun on a monochrome screen. Nothing remarkable there,
except that this one was only 11 K in size - that's right, 11,000 bytes!
eventually the 5.25" floppy wore out...

It did have one bug. There was no way to shut it down except by rebooting,
but in the old DOS days that didn't take long.