The notorious “eat apple get longer” game. Reimplemented so much that Wikipedia categorizes it as a genre, not a single game.
The first version I played much of was on a Nokia phone, but the game has been around much longer than that.
I'm sure I've implemented at least a few versions of this. One notable version was a local 4-player mode implemented in Code.org's Game Lab:
https://studio.code.org/projects/gamelab/Qb01-HiqbEWTwcY-1bFZjA