Mind-blowing video game fact?

What is your most mind-blowing video game fact?

This is the most mind blowing that I've actually encountered without being told.

In PC version (at least) of the old Star Wars arcade game each level has three parts: shooting TIE fighters in space, shooting turrets on Death Star surface and the trench run. The first two hardly change, the last has more complicated obstacles after few first levels.
You can start at level 1, 3 or 5 - which doesn't really matter as the game goes on till level 99. And then starts again from 1. It takes couple hours to get to 99, a test of stamina and concentration more than skill.
And the mind blowing detail is that if you get to the end of level 99, you are rewarded with a simple line image of Vader in the back wall of the trench - which you get to see, after playing hard for couple hours, for about three seconds!
(If you have extra shields left you can intentionally fail firing the torpedoes and do the run again to see Vader for couple more times.)