This is a large, ferocious arena with a large number of participants, with the basic rule that the huge eats the small.
You convert into a worm, the tiniest worm in the arena at first, but don't worry about it; use your foraging abilities to make yourself into a voracious worm, devouring everything in sight. You will develop stronger as you consume more food, and once you are large enough, you can eat animals that are smaller than you.
You'll eventually turn into a super gigantic worm; else, you'll be easily eaten by others.
Warning: this game is very addictive