This creature is called a Sniffer and it's part of a game concept I've been developing (the game is called BOL - Ball Of Light).

In it, the hero is trapped in an underground realm with very limited visibility (so advancing is very slow and careful).

The Enemies are all hunters that use senses other than sight - introducing (hopefully) interesting game mechanichs, so the Sniffer is a creatre that hunts through smell (I'm sure you guessed it). However, they are smaller than you and cowerdly and will not attack unless there are two or more of them, so one will follow you around, and if you're unlucky enough to encounter more - or unskilled enough to avoid them, you'll have to escape until you cross a body of water, or pass a stronger source of smell.