Tearaway Thomas

 At any time, type any of the following (screen will flash to let you
 know if it worked):

 NORMAL             Disables all active cheats.
 LIFE IS TOO SHORT  For infinite lives.
 IRON MAN THOMAS    For invincibility.
 ANY LEVEL          Activate stage skip. (Down cursor to advance level and up to go back)

 At the end of the very first level, avoid the exit and instead jump
 onto the top of the trunk.  Jump up and you will see a star. 
 Collect this to skip to level 5.

 There is a secret level located on level 1.3, and can be found by
 climbing up to the ninth branch of the tree (which is the one with the
 birds on it) and running off the end.  You then will be whisked off to
 a room containing some diamonds which can be collected for extra
 points.