Flushing Edge Interactivity

We live in an age of Video Games where the cutscenes are acted out by actual actors in ping pong ball covered jumpsuits, incredibly complex scripts are written to give the player meaningful relationships with NPCs, and advanced physics engines are implemented allowing the player to fiddle around with their surroundings in a nuanced and sophisticated manner.

Imagine the public outcry if a developer decided to feature restrooms in their video game in which the toilets could not be flushed.

If you imagined burning skylines, plundering and wanton murder, congratulations: you are a video game developer.

Yes, this trope describes interactive toilets of all sorts, that, other than being able to be flushed, serve no purpose whatsoever. This has the potential to feel utterly out of place in a game that takes itself even remotely seriously.

The trope name is an allusion to gaming (particularly on the PC) in the early-to-mid-1990s, back when being able to interact with anything that wasn't gameplay-critical was regarded as "cutting-edge".

Examples of Flushing Edge Interactivity include:

Surprisingly averted in Mother 3. Chapter 8 has a whole toilet dungeon, but none of the toilets there can be flushed.
Mass Effect 2—but go to the wrong restroom and the on-board AI will get snooty with you.
Proudly subverted by the No More Heroes series, in which every save point is some kind of toilet, and your file data is on toilet paper.
Duke Nukem 3D has interactive toilets, but then again, a lot of stuff is more or less interactive in that game. Toilets and urinals can be used (the way they're typically used...) every few minutes to restore 10 health points, and they can also be destroyed to yield a stream of water that can heal the player to maximum, though very slowly.
- In Duke Nukem Forever, the toilets can be used. Unfortunately, one of the toilets has already been used...and that person didn't flush. You can get an achievement for poking the matter in the unflushed toilet.
The Darkness.
The Chronicles of Riddick: possibly lampshaded as flushing every toilet in a certain area gives the player an easter egg.
Prey.
In Postal 2 the player is actually able to wee the whole place upside down, and in fact even urinate on burning victims—the toilets, however, still serve no function.
Portal and Portal 2.
- "Your business is appreciated."
Dead Space 2.
BioShock 2.
Yume Nikki.
Subverted in the Fallout series as the player can actually drink from the toilet (at a cost!)
The Max Payne games have such toilets and many other objects than can be activated just for the sake of it.
Inverted in an episode of The Simpsons where Homer was wearing a Motion Capture suit during a demonstration of the technology and went to the restroom. Everybody saw his avatar going through the motions of using a urinal, but it was a generic park background.
Final Fantasy VI.
One house in Jabless Adventure has a toilet which you can shoot with your gun to flush it.
The first Leisure Suit Larry game has a toilet in Lefty's Bar that can be flushed. Doing so floods the room up to the ceiling. Have a Nice Death!
Animal Crossing.
Deus Ex.
- Deus Ex Human Revolution takes it further with working sinks and hand dryers as well, so you can role-play going to the bathroom...if you really want to.
The Suffering features a restroom very close to your first cell and is the location of the Cutscene where you pick up Torque's first Morality Pet. Needless to say, the toilets needlessly work (though if your graphics card isn't up to snuff you can expect the most geometrically unsound flush imaginable).
In Bully, the toilets and urinals can actually be used by Jimmy (though only to urinate), with a flush sound being heard should you choose to do so. You can also place firecrackers in the toilets. All of this is purely optional, however.
A great many fan-made ZZT games. Keys hidden in the toilet's water tank are also a favorite.