Yars' Revenge (Atari 2600)
Yars' Revenge is a shooting game made by Howard Scott Warshaw, who also made the infamous E.T. Unlike that map to Area 51, this game was surprisingly one of the classics.
Kill the Swirl in mid-flight and a flickering black line should appear along its Y-axis. Now, stand upon it and hold any vertical direction before the status screen appears. If done right, the letters "HSWWSH" will replace the score, which some know as referring to developer Howard Scott Warshaw.