Donkey Kong
Hidden levels
Jungle Hi jinx
Jump off of the wall at the very start to reach the trees on the right.
Follow the downward banana arrow and jump down to the spot its pointing-a
steel barrel pops out. Throw the barrel off the wall to the left and ride
it to the right through half of the level, steam-rolling over anyone who
gets in your way. Eventually, you crash through a wall and into a hidden
room.
Jump down off the tree with the 'G' icon in it and land on the odd patch
of ground below to find a barrel. Go left to the nearby wall and hurl the
barrel to find a room with a bonus game.
Ropey Rampage
Jump down from the tree after the second swinging rope.
Land in the barrel and shoot out to the right, fly through the wall, and
land in a big banana bonus room.
Jump down the pit just left of the arrow that points toward the exit to
land in a barrel that fires you up into a bonus game.
Snow Barrel Blast Shortcut
All the tough barrel-jumping starts right past the barrel with the Ramby
above it. There's a hidden barrel that you can
jump to near the very beginning of the hard barrel jumps.
It's the last barrel with no star on it, so when you get there shoot strait
down. Its off the bottom of the screen so you have to take a blind jump.
Vulture Culture
Shoot out of the barrel that has two birds to the right. Time the second
bounce just right so that you land on the side of the next wall. You open
a secret door.
Reptile Rumble
Grab the normal barrel that's just past the first 'DK'-marked barrel and
use it to bust open a door in the wall to the right for a 1up.
Grab the barrel that's sits beside of the 'DK'-marked barrel just before
the snake pit (kill all the snakes first) and throw it at the wall on the
right to find a hidden entrance.