Level select -
Choose a world from the main map. Hold [Tab], type "openall", and press 
[Backspace] to access any level on that world.

Cheat Codes -
While playing a game, hold [Tab] and enter one of the following codes:

Cheat Code - Result
points - Full energy 
goldens - View all gold coins 
lives05 [Backspace] - 5 more lives 
lives20 [Backspace] - 20 more lives 
lives50 [Backspace] - 50 more lives 
moveray [Backspace] - Use cursor keys for free movement