Pillars of doom.
Pillars, fairly harmless, not always, say blades are hidden in them, walk near the pillars and they start spinning and the blades hidden in the column extend out on a pivot and the whole pillar as now spinning, what those blades don't get you. They don't have to be full pillars, could even be half pillars, the blades don't have to be hidden, could be always on show, could be set to spin when the player is close, or always spinning.
Pillars or plinths with spikes on them, if the player gets to close they fire out like missiles.
Pillars or plinths could also give out electricity rings, or even fire/flames, perhaps always are perhaps when the player is close.
Guns attached to pillars, when off they face the floor, get close and the pivot up, and will shoot what's in line with them, perhaps you can shoot them off the pillars/plinth, leaving a normal plinth/pillar.
Revolving wall
You've seen the films, the wall or floor and wall revolve, you tread on it and it revolves and you are in another room.
Trap door
Stand on it and fall into a room below, or the trap door opens to a steep ramp and you slide down to another level.
Collapsing ceiling/floor
Perhaps it disintegrates into chunks that fall on you. Could also work with a floor.
Moving walls
Disorientate the player, have the walls move about, one could make a maze of these, have the player go back into rooms they have been in, only the walls start moving and now its all different, would be hard to negotiate the room if it had walls that moved about, perhaps set by proximity triggers, or just being in a zone. You could never trust the level, at any time walls may move right in front of you, and bar the way or just plain confuse you.
Walls could also come from the floor, usefull for if you wanted to seal the player in an area, say to fight a boss, when a trigger is made, the walls could go back down and the player can move on, the holes in the floor, for the wall to move through could be represented with decals on the floor.
Moving walls that crush, set them to move and crush whats caught by them, like have spiked walls that move together, great for making a player run though a level as the walls are closing in.
Electric floor plates
Just dont stand on these, just a simple decal that dishes out pain when walked on. Could be moveable by being programed by the editor of the level. plates could have editor options, like give health take health, when to go on, when to go of, if they move etc.
Trap doors that bring stuff.
The foor or wall opens up and a podium comes up bringing something, could be good or bad.
Gas trap.
gas area, walking in this area will bring damage, perhaps void if wearing an item.
Lazer defence barrier.
lazer shield, have this unit create a barrier of defense, see its being made, like powerup, great to hide behind, or protect areas, or bar entry, perhaps used with other items like the trap door that brings stuff, see above.
Could be a simple animation to make this, like two stuts come up, then pull apart, in between them is the barrier, so as the struts open the barrier gets bigger as the struts open out.
Force field.
Force fields that blast the player back, be able to set the distance and damage.
Footplate riddle.
stand on footplates in an order or have so many that have to be trod on, perhaps changing the decal image, red to green, these will then activate something else, like opening a door, or switching something off. Could also be on walls, or perhaps have to be shot at, destroyed to have an action. Shooting them changes the deacal, like a light goes off, or activate message read out is gone.
Question machine unit
Unit that asks a question to open it, already has the script for that, do a search for my threads in scripts.
Black hole.
Vortex, just use a decal, draws the player to it, like sucks them to the thing, or to the centre if its on the floor, in the centre we could place a teleporter or whatever we choose. This is great for gateways, like opening a rift in time and space.
