Fireflower - It gives Tux the ability to spit bouncing fire bullets.
Running - It enables higher and wider jumps and other things that require some kind of 'boost'. Running is done by holding down the 'run' button.
Buttjump - An ability that lets Tux crush boxes from above and destroy some enemies that cannot be harmed by a normal jump. It is performed by jumping up into the air and then pressing the Down key while in the air.
Getting more and more angry the longer he is left.
Blowflyer/BalloonTux - A temporary limited action in which Tux fills his body with air (helium) and is thus able to fly for a short time, i.e. as long as he can go without breathing. The end of the flight is announced by Tux changing color and catching for air.
Iceflower - It gives Tux the ability to shoot ice bullets. Ice bullets will not bounce like fire bullets, but will shoot out in a straight path towards the enemy. When the ice bullet hits an enemy it will freeze him for a short time
Slider - Tux will be able to make use of smooth terrain by using the slide action. By using the slider action Tux will jump on its belly and thus slide speedy down the hill. Terrain that is formed like a ramp should allow him to make huge jumps, which would be impossible without the slide action. While sliding downhill Tux shall be invulnerable by normal enemies, however special enemies with spikes or so, might still be able to stop him.
Flapping - Once in the air, Tux should be allowed to flap with his wings. They are not enough to let him fly, but should allow him to get some additional air-time (like a small double-jump).
Soap - Tux might be able to eat some soap and thus be able to spit out bubbles, bubbles themselves should be usable as steps to reach higher places and might be able to capture enemies.
Rope - Tux will be able to use a rope (in one form or another). The rope should be useful for both swinging around and capturing/disabling enemies.
Boomerang - Tux should be able to collect and use a boomerang on some levels. This could maybe hit 3 badguys and then come back to Tux, and of course not be usable against Flames.
Swimming - Tux could be able to move a lot faster in water than on land, and he could be able to jump higher when jumping out of a pool of water - like real penguins.
Pogo Stick - The Pogo Stick will give Tux the ability jump higher and to break blocks when he jumps on them. This will work simular to the NES game Ducktales and the PC game Commander Keen.
Dive - When jumping from a great height, Tux should have his beak facing down, like a dive. It would work well with the swim ability.