Two orcs
Officially better than you, according to PoN
Boxes with something smelling/making noise/moving inside. Sometimes it's a dangerous monster best left alone or killed without opening the box, sometimes it's a potential ally, sometimes it's some magic artifact. Sometimes it's just a cache of food gone bad, maybe being feasted on by vermin.
Things that link back to earlier things. A diagram for an incomprehensible machine. The power source for an earlier machine (to turn off or on). A half finished experiment you can finish (for good or ill). A secret ladder that goes on and on to a tiny sublevel. A hunchbacked servant or automaton that is servile but possibly dangerous. Cumbersome equipment (think diving suits or firefighter suits) necessary to deal with some area but which changes how they interact with the world (narrow field of vision, slow movement, limited oxygen). On that note, a room full of gas where you need to hold your breath while exploring.
Things that link back to earlier things. A diagram for an incomprehensible machine. The power source for an earlier machine (to turn off or on). A half finished experiment you can finish (for good or ill). A secret ladder that goes on and on to a tiny sublevel. A hunchbacked servant or automaton that is servile but possibly dangerous. Cumbersome equipment (think diving suits or firefighter suits) necessary to deal with some area but which changes how they interact with the world (narrow field of vision, slow movement, limited oxygen). On that note, a room full of gas where you need to hold your breath while exploring.