You select your stage of the five available before moving to the player select screen.

Aiming your cursor at a penguin selects it for you. Each has different characteristics - fast snowballs, good acceleration or large snowballs. You can alter the handicaps of these penguins by moving your cursor over the ends of the 'Handicap' bar.
There are also four custom penguins, and you can alter their stats to suit your personal taste - the 'Handicap' bar indicates how these compare with the standard penguins.
Pressing start when all players have chosen begins the round.

Snow begins to fall from the sky, settling in a few distinct patches. Running over to one (with the DIRECTION BUTTONS), you discover the first problem - you're trying to run across ice.

Inertia is now a consideration.

Managing to steer yourself back on to the snowpatch, you collect some snow with the COLLECT button. A snow-store indicator begins to grow on your information bar.
To throw a snowball, you hold down the THROW button. A snowball will be built from your snow-store - holding down the button for longer builds a bigger snowball. Releasing the button throws the snowball in the direction you are facing. The bigger the snowball, the more damaging it is.
As you collect snow, the snowpatch disappears and as long as you stand on it, it won't grow. This keeps the gameplay dynamic.

Holding the COLLECT button brings up an indicator for more precise aiming - moving the DIRECTION BUTTONS will alter your aim.

You aim and throw a snowball.

(OUCH!)

Overjoyed with your new-found talent, you paddle across some water. Some very, very cold water. You lose energy. Running across water is alright for short distances if you're already going quite fast, but don't stand still with your toes wet because it's quite hard to get moving again.

Two standard pads are needed to control the penguins.

In 2-Player mode, the buttons are:

D-PAD - Move penguin.
CROSS - Gather snow, aim.
SQUARE - Build snowball.

In 4-Player mode, the buttons are:

D-PAD - Move player 1 penguin.
L2 - Player 1 gather snow, aim.
L1 - Player 1 build snowball.
TRIANGLE, SQUARE, CIRCLE, CROSS - Move player 2 penguin.
R2 - Player 2 gather snow, aim.
R1 - Player 2 build snowball.

You'll have to reset the game yourself after each round - pressing START and SELECT on controller one will do this for you.