FFA Mode

FFA Mode, short for Free-For-All Mode is the first and one of the currently available three game modes.

In this mode you are on your own against all the other players in the lobby.

Your objective is to grow and to become number 1 on the leaderboard (and to try to stay there). The places on the leaderboard are determined by total mass of the player's cells. You can consume any other player in the lobby.

In this mode you can use skins, although you'll still have a colored outline around it.

Strategies
One common strategy used is to eat pellets until you have 150-200 mass and attack large cells with viruses. The large cells will have many small cells for you to eat and will be too slow to avoid you. This tactic has considerable risk from the frenzy of cells attacking the weakened larger cell, but it also has a chance of gaining a lot of mass in a short amount of time.