One was based on a stripped version RANGER.NSG -- the number of digits to order was decreased from 9 to 3.
Another was based on OLYMP.NSG. Time was not counted and length of a track was 8 spaces long. To win player had to push right arrow 8 times.
Other .NSG written so far were too complex for that parlor, but I wanted at least 3 games. So I came up with the one where player (π) is presented with a character-art picture of a lion (On-n~) and is required to push space bar, at which point arrow slowly flies towards lion and kills him.
Once I invented the game, it became just a matter of principle to make it little bit more playable and turn it into .NSG. I added some random delay before displaying a lion, counted time before shot and presented some smart comments about players' shooting skills based on that time.