Convert the sleeping gas trap to just “gas trap”, and make it scale based on the difficulty. Each individual trap releases a single type of gas; which type is partially dependent on the level difficulty. At low levels, they all emit sleeping gas like normal. At higher levels, they emit stunning hallucination gas like container traps, clouds of poison gas, and maybe even nastier gases that reduce speed or miasmas that cause illness.

On deeper levels, land mines cause a fiery explosion in addition to their existing effects. Player-placed land mines get a bit trickier; a simple implementation will just consider the depth of the level the trap is on, but a more correct one would track via a field on the land mine object (in case it is picked up and carried around to another level) whether or not it will produce an explosion when triggered.

Dart traps eventually shoot “big darts” instead of little darts, which do more damage than the little darts, although internally it’s still shooting a regular dart object.

A plan for magic traps to scale according to the depth they appear on. All these effects are still triggered just with the same magic trap - this isn’t adding new trap types.

Possibly remove polymorph traps as an independent trap type since it’s one of the options here.

Container traps’ effects scale based on dungeon level (ideally on the level a container generated, not on the current level, so a player can’t bring a chest up to level 1 to make it use the weakest possible trap.)

In addition to adding some more effects, also add some effects which cosmetically are the same as other ones, but are more or less damaging. This would, however, make untrapping containers even more useless than it is now; perhaps a trap should stay armed even after you set it off. Another idea is to give certain traps an arming item, like a potion of oil for the fire effect and a land mine for the explosion effect. Successfully untrapping it will deposit the arming item into the container.

Also, make container traps independent of Luck, because currently they encourage the player to ignore containers until Luck is maximized.

Anti-magic fields in Gehennom can attempt to cancel you or your gear, and apply the cancelled status effect.

Deeper in the dungeon, rust traps might target your pack instead of your armor or gear, and could possibly be renamed to “water trap”. On deeper levels and particularly in Gehennom, rust traps phase out to be replaced by acid traps. These deal corrosion and acid damage (and quite a bit of it, like having multiple potions of acid dumped on your head).

Pits get deeper the further down in the dungeon you are, which makes them deal more damage, might cause wounded legs with a chance that increases with depth, and take longer to escape from (or are so deep you can’t climb out at all). In Gehennom, they might deal extra damage on account of being designed and put there by demons. The extra depth could be conveyed to the player by “You fall into a [very] deep pit!”

Falling rock traps can dump multiple rocks onto you at once, up to (depth/4). Damage is taken for each rock. If a trap would drop 4 or more rocks on you, it may instead drop (rocks/4) boulders on your head instead. Helms should be less effective at reducing damage from falling rocks, and almost useless at reducing damage from falling houlders.

If multiple boulders are dropped, they might be dropped on nearby spaces as well, so that a pathway might end up blocked.

Magic traps’ blinding and summoning monsters effects should be split up, since both at once tends to make them much more fatal, especially to early players. Alternatively, make the summoned monster selection with a lower-difficulty pool of monsters.

Statue traps generate monsters with a +5 difficulty modifier (though this might be too high). This is because a statue that surprisingly turns into a level-appropriate monster isn’t usually very threatening.

Scale the damage from an anti-magic field (caused by having MR so you don’t get drained of magic power) to your maximum HP, or possibly by your experience level, rather than a few d4s that are usually meaningless to any character with a few levels. Or have it be based on your Pw maximum, with a higher maximum incurring a larger amount of HP damage.

Make arrow traps multishoot arrows at higher level difficulties.

Pressure plate traps that cause all the doors of the current room to close and lock (doorways without doors could turn into iron bars or, on deep enough levels, all doors could turn into iron bars). Triggering this automatically removes the trap. Generated very rarely, and has special generation that occasionally makes it appear just inside a door to a throne room.

Several things relating to making the upper dungeon feel more “eroded” or exposed to the elements/other adventurers, in keeping with NetHack flavor that other people have been seeking the Amulet:

• Falling rock traps on shallow levels come “pre-disarmed”, which is to say that they have already been used up and so should consist of a pile of rocks on the ground underneath a falling rock trap with no rocks left in it.
• Rolling boulder traps on shallow levels generate without boulders or with out-of-line boulders.
• Traps with ammunition can have a few pieces of that ammunition lying on the appropriate space.
• Dilapidated armories.
• Monsters on these levels are likely to generate with zero-charge or low-charge wands or other items.
• Fewer items lying around.
• Randomly destroyed walls.
• Fake bones piles (see below).

Note that this has been partially implemented in 3.6.1 with the addition of fake bones piles that come with a pre-disarmed trap if applicable, although that was aimed less at adding ambiance and more at helping players avoid early traps.