How to view the Doom 64 demo of map level 32, HECTIC:

Go to Doom 64's Options menu, choose PASSWORD and enter the following password:

RVNH 3CT1 CD3M 0???

(Note that the password is a stylized version of the phrase "RUN HECTIC DEMO".)

If entered correctly, the Password screen will clear, and the Options menu will
be re-displayed.  Press Start (or select the RETURN item from the Options menu)
to return to the "NEW GAME / OPTIONS" prompt.
After 20 to 40 seconds the game's title sequence will begin, followed by the
usual three game demos.  This can take up to five minutes.
Following the third demo will be a new, fourth demo, which shows successful
completion of level 32, HECTIC.  All keys are acquired, and the special exit is
accessed.  This demo's running time is about 1:45.

The HECTIC demo will not remain in the demo roster; The game will automatically
revert back to the normal 3-demo cycle.  In order to see it again, the password
must be re-entered.

Background: Map 32, HECTIC, is a special level of Doom 64.  It is accessible by
using the first secret exit in the game (see the DoomHelp page for details), or
by entering one of the special Doom 64 passwords for map 32.
In HECTIC it is possible to gain access to a special exit teleporter.  Leaving
via that exit will unlock the game's hidden FEATURES menu (cheat-options menu).
For more details on Doom 64's Features menu, see the DoomCode document.