This goes again to the nostalgia category. I really would like to make my own version of Commodore 64’s Stix.
This is a classic game from the year 1983. Below is a screenshot from C64 emulator:
The idea is to fill 75% of the playing area by turning 90 degrees from the direction the player is going. Kind of addictive game!
This idea could be refined to something more interesting…