Go to the Options screen and highlight "Level." Next, press and hold Start
on Controller Two, then press and hold A, B, and C on Controller One.
While holding these buttons, press Up and then Up-Right on Controller One.
If you've done this Right, the difficulty level should have "!!!". During the
game, you can pause and press A to refill your web-shooter, B to refill
your life, C for five seconds of invincibility, and all three buttons to skip
to the next level.
Go to the Options screen and select "Nightmare" difficulty. Play the game
and get into the first level warehouse. Proceed to the Right, past the first
thug and then past the German Shepherd. Next, jump on the first crate
and crawl to the Right. You will go through the crate and to the Right will
be the forklift boss.