No no no, you guys... This is a mini-game in Warcraft III, or rather, a map designed in such a way with events, that the game plays like an arcade style game.
It works like this, you use three keys, two move your character one space to the left or the right, while the third key executes a special attack(killing all the sheep in the field).
You have your paladin at the bottom, while sheep come running from the north towards your paladin. If your paladin is hit, he loses a life. Dodging sheep earns you points, and can give you a special attack. Using the special attack kills all sheep on the field at once, give you points equal to the number of enemies killed times the point modifier(that builds up as you dodge sheep, goes down to 1 when the special attack is used).
There are four different things in the field that runs toward your paladin:
Small sheep: Runs fast, and goes on one trajectory, but can change its trajectory by a few degrees.
Big Sheep: lumbering sheep that move slowly, they also follow the same trajectories as small sheep.
Pigs: Runs fast, and will change its trajectory towards the direction your paladin is in.
Villagers: When your paladin runs into these damsels in distress(as it were), he gets a bonus life.
Now if any of you has read this so far, THIS IS ALMOST NOTHING LIKE THE EXPLODING CRITTERS THING FROM WARCRAFT II AND STARCRAFT. Its a fun little arcade style game that demonstrates the versatility of Warcraft III's map editing tool. Well, it does involve exploding critters, but not from clicking them.