Blobie is best played while shouting "Get over here!" at the top of your lungs, over and over.
Use the mouse to move around, and fire your hook with the left click (or W). Any opponent you hook will be dragged toward you, increasing your score as well as the size of your hook.
It's one-hit-kills, so play it safe!
You can't move while attacking, so it's best to only fire off your hook if it won't come back to bite you.