One-shot concepts

2014-08-23 (updated 2014-08-31)

Since tags are for concepts recurring in multiple games, I thought I'd start a list of things that supposedly exist only in single game. Undefined elements tag is in general easy-ish way to find games with these, tho it's unreliable as some may be recurring but unnamed.

* Shovel Knight – destructible retry points.
* Life Goes On – avoiding retry points or triggering them in specific order is used to solve puzzles.
* Closure – unseen things don't exist.
* Call of Juarez: Gunslinger – narrator changes reality by correcting, adding to or otherwise altering earlier statements.
* E.Y.E: Divine Cybermancy – player character can get hacked.
* Frozen Synapse – simulated previews of future events before committing to them
* Gunpoint – remote rewiring of enemy systems.
* I Am Alive – overexertion
* Planetary Annihilation – using habitable planets/asteroids as WMDs by crashing them into other such.
* Receiver – excessive gun handling simulation.
* Risk of Rain – bosses spawn every 5 minutes regardless of anything.
* Snapshot – copying parts of a level and pasting them elsewhere to solve puzzles and generally progress.
* UnEpic – some enemies steal the player's weapons and use them against them.
* Wanted: Weapons of Fate – bullet curving
* Baldur's Gate – Biff the Understudy who replaces and recites lines of characters that have unexpectedly died or the player has killed before their part in the plot.

Generally I'm not sure if these should be identified as including "unique concept/mechanic" or not, but this is a list of games with such. Technically these should at least all have gameplay innovation or something, though some may seem too insignificant for it.

Following games have concepts that need to be named because games using similar enough concepts have surfaced:

* Antichamber – world is altered by viewpoints and such...
... other occurrences: MIND: Path to Thalamus possibly uses similar ideas, Sightline definitely uses them.
* Phantasie III – player character getting dismembered does not end the game and player continues on without said limbs.
... other occurrences: Die by the Sword, NeverDead, technically also Dwarf Fortress, Metal Fatigue, and some others.
* Perimeter – NPCs actively alter the game world geometry (outside of collateral damage).
... other occurrences: Minecraft, Perimeter 2, Maelstrom, etc.

re: One-shot concepts
* Planetary Annihilation – using habitable planets/asteroids as WMDs by crashing them into other such.
This is a not that uncommon sci-fi weapon. Though sometimes it is not as obvious as colliding worlds together. Moving large objects around can be used for altering tides, daylight cycles, seasons, and other things. The 'attack' can sometimes go unnoticed or at least no one is quite sure what's going on or who did it. For instance, in Asimov's Robot series, there is a plan to change the moon's orbit slightly to affect the rate at which heavy radioactive materials rise to the surface of the earth via a liquefaction-like process (I''l not no spoil on how it turns out).
Footfall by Larry Niven. A generational fleet carries a civilization from solar system to solar system where they wage war on other civilizations by throwing their own asteroids into collision paths with their inhabited planets (among other tactics).
In the Doctor Who universe, the original 22nd Century Dalek Invasion of Earth began with the Daleks bombarding Earth with meteorites
Iron Sky (2012). Meteorites are flung to the Earth with large spacecrafts.
Starship Troopers had the insects launching meteorites at Earth.
Other works include The Mote in God’s Eye, The Moon Is a Harsh Mistress, Titan by Stephen Baxter, and Children of the Lens.
Carl Sagan warned, in a scientific context, any system that could deflect an asteroid by altering it's course could also be used to cause otherwise harmless asteroids to collide with earth, even on accident.
Several proof-of-concept studies have proven asteroids-as-weapons to be a sound tactic. Advantages include initial confusion as to exactly what happened as a large asteroid impact can mimic a nuclear blast, but without the radiation and difficulty in tracing the perpetrators. Disadvantages, for now, is relying of finding the right asteroid, on the right course, at the right time, that can be deflected to an intended target. A country gearing up for war might want to collect thousands in orbit in preparation. Lots of time and patience required.
Roberts Space Industries apparently allows this though it doesn't seem to be an intended design (just something players worked out how to do). Players use this on small and large scale attacks.

2014-08-25 (updated 2014-08-25)
Well, the list is about video games solely, so occurrences in other media are ignored.

But yes, asteroids and other large objects are used in scifi as cheap WMDs. Dunno about what Star Citizen allows, so I can't comment on that.

Left Behind: Eternal Forces has a rare concept. Killing enemies is the least beneficial use for them. A saved enemy is immediately twice as beneficial and they become an additional resource for later use.