These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Nightmare Fuel: The Face from 14/? appears in Neftelia's White Maze when the lights are turned off. It's method of summoning, and appearance, is already reminiscent of Uboa, and when you step on it, it laughs, removes the doorways, and causes several of itself to appear all over the screen rolling their eyes and laughing. You have to hold down SHIFT to escape, there's no other way.
Activating a ridiculously obtuse and rare event in the empty cavern causes a giant red face to eat you, taking you back to the menu.
Taken Up to Eleven in the sequel's appearance of Face. It appears in the Random Maze, but instead of trapping you when you step on it, it just... disappears and laughs mischievously. Players will likely forget about it, but every time they press Search from then on out, Face starts stalking the player more and more. It starts off with them just appearing for a second and laughing on most screens, but eventually the player turns grey, laughs start appearing before you spawn, static starts appearing on the screen, and eventually, you're summoned to a special area that ends in a Jump Scare.
Tear Jerker: The whole game has a sense of melancholy about it for the most part, but the orange-skied city truly stands apart. Especially when you accidentally kill one of the creatures in the buildings the other one just stands there....
A large portion of the first game is spent exploring a large continent of sorts you can fall onto. You return to it in the second game, but this time it's flooded, and you most fly over it in the UFO, while a much more solemn reprise of "ridin' in mah UFO" plays.