Freakin' Funky Fuzzballs is a top-down puzzle video game written by Ian Currie and Robert Koller for DOS and published by Sir-Tech Software.
In it, a fuzzball must navigate several maps and avoid the "enemy."
In fall-out maps, tiles change colors when stepped on and disappear when they turn blue.
In static maps, the tiles change from dark to light pink.
In addition to keys, there are an assortment of other items- Computer Gaming World called the game "an original twist on old arcade inspirations ... an addictive pursuit reminiscent of Tetris".