If you walk right up against the left urinal in the toilets in E1L1, you can see a US style phone number on the wall. Anyone got any ideas as to what it refers to?
Turn on god mode, fly up really high with the jetpack, then let yourself fall to your doom. Of course, you won't die, but turn on rear view mode (hit f7), and you'll see duke's death frames stuck in a loop.
If you have the registered version, rename the duke3d.grp file to something else. Then copy the duke3d.grp file from the shareware version to the game directory. Now go and play a level from episode1 1, cheat for all the weapons, and try them out. Things seem rather weird using the weapons when half (or all) of the graphics for them are missing. If you start the game normally, and the first demo is not from episode 1, the game will crash (because it can't find the required map). The solution? Either make sure the first demo is from episode 1, start the game with command line parameters to go directly to the desired level, or just delete (or rename) all the demos.
In the right hand stall in the E1L1 toilets, there is what looks like an email address (without the @ symbol). It is really small, and right down at floor level (easiest to see in BUILD).
Go to the street in E1L1 and put in the god mode cheat (for the unlimited jetpack) and dncashman. Now fly around while holding down space to draw patterns in the air with bills. Don't go too overboard or you'll end up exceeding the game's limit of sprites and crash the game.
Turn on no clipping mode and walk through a mirror. If you do it in v1.3D, you'll end up in a mirrored version of the original area. Due to how mirrors work in Duke3D, there is a limit to how far away from the mirror you can go (exactly how far depands on the map design). If you go too far, you'll end up dying. If you do it in v1.4 (or walk through a broken mirror), you'll just get the HOM effect, but you'll be able to see out the mirror just normal.
In E1L3, up high in the chapel, there is a haging monk. Remember the monks from Rise of the Triad?
If you have v1.4, turn on god mode and no clipping mode and walk out the window at the start of E2L1. Walk over to the opposite side of the spaceship, and you can see its name: U.S.S. Framerate.
In E1L5, in the area where you turn on a shrinker machine, get a jetpack and fly into the cave where the machine is. You'll find a message inside from the level designer.
In E1l3, in the chapel, you can press space on the altar and shoot out the stain glass windows, go into the now opened passage, and at the end you'll find a "DOOMed" space marine. If you've played Doom deathmatch (who hasn't?), it'll be instantly recognisable.
There are two occurences of "1138" in E2L2. One is displayed on a security monitor in a secret area, the other is in small grey letters on the wall under the EDF logo. Anyone know what this refers to?
If you shrink the cheerleaders on the Stadium, they unshrink bigger than before.
You can get the enemies to get squished (or simply kill them) under the vertically opening doors. Afterwards, you'll get a stringy bit of mush stretch up when the door is opened.