Bastian Pflieger made a snake style game for the Gameboy Advance. You can get the download from GBAdev. Here is what the author says:

From time to time there appear some special symbols to collect. Every special symbol has two effects, a good one and a bad one. So its up to you to collect it and hope for the good effect or wait a few seconds until the symbol disappear. For example onecould cut down the snake length or increase it a lot, another one ends the level or make you nearly invisible and so on