ADVENTURE ISLAND

You can get extra lives:
You'll get an extra Higgins at 50,000 and 100,000
points.

To see what the next Boss is going to look like try
pressing PAUSE right after you knock off the Boss' 
head.

If you jump just before the "G" sign at the end of area 1, you'll
uncover an egg containing the Hudson bee. Pick up the bee for
unlimited continues. Just press the left arrow then Start when
your game is over.

Bonus Rounds:
Bonus Round?? Yup! Here are a few Bonus Round locations:
Area 1, Round 1, Section 3: Stand between the fourth and fifth
totem poles and wait for the platform to appear.

Area 1, Round 3, Section 2: Look for the key egg right on the
stone ledge just before the dropping platform. Once you have the 
key the platform Iifts you to a bonus level instead of dropping.

Area 2, Round 3, Section 2: There is a hidden egg on the stone
section right after the "2" sign, near to the platform. Grab the 
key and the thind platform lifts you to a bonus level.

Area 3, Round l, Section 2: Pass the pair of frogs and then jump
down two more steps to a long, flat area. Run back and forth and
toss your axe and a platform appears to take you to a bonus round.

Area 4, Round 3, Section 4: Jump to the third small icy tower. Jump
and you'll find a hidden egg. Grab the key and the next moving
platform, just before the campfire, takes you to a Bonus Round.

Area 5, Round 1, Section 1: Grab the hidden egg with the key right
before the cloud platforms. When you jump onto the last cloud 
platform you'll go to a Bonus Round.

Area 6, Round 2, Section 1: Jump over the rolling boulder and then
right after the rock you'll find a Bonus Round. An elevator takes
you up.

Area 8, Round 1, Section 3: You'll find the Bonus Round past the
second rocks with the hidden pot, and before the egg with the 
Eggplant. Remember not only do these Bonus Rounds give you extra
points, they also often let you get past especially difficult 
obstacles since after the Bonus Round you're at the end of the 
section.