Perfect Infomation

Interestingly, there hasn't been much of an attempt to formalize the definition of the most common selling point of abstract strategy games: 'perfect information.' Maybe it's just me, but there seems to be some argument over what counts as perfect or imperfect information, but where there's agreement, it's just some vague concept.

According to Wikipedia, a game has perfect information if "each player, when making any decision, is perfectly informed of all the events that have previously occurred, including the 'initialization event' of the game." While this definition is nearly acceptable, there are some factors that put this into a bit of a debate.

Whether the definition needs changing is still open to discussion, this piece is concerned with where information within a game is not obtained.

For this to make sense, let us look into some factors that some people might agree are not accessible to a player's knowledge:

Things beyond our control

Chance and Randomness are rather interchangeable, but they define cases where scenarios can or fail to happen if random factors beyond the capabilities of the player are met. From the creation of starting setup to determining possible moves or circumstances, chance is determined through generators and sometimes a means to interpret its results.

The former is seen as more incompatible to perfect information while the latter is accepted as long as it doesn't include anything beyond the player's control happening outside the game. Some games use random starting states as a feature to create unique games without compromising on rules of play or other relevant information.

Backgammon can be a game of intelligence but plays are determined by the roll of the dice, which can drastically change one's strategy, a common contrast from Chess. Some simulator-type games use some type of randomness to imitate outside factors or the aleatory nature of environments or situations one can encounter. 

In some cases, chance is usually augmented by either choice or advantage. Choice is where players can choose how these random factors, usually from rolling dice or drawing cards, will be used in a turn. Advantage is where a player has an additional, usually permanent factor that is always added to a random one. The two can also come before the roll, e.g. a choice to do which roll or an advantage that is added based on the result of the roll. 

Generally, the point of contention is whether having some random initial setup should be included in context of perfect information or outside it.

Things one does not know

When a player does not fully know all the relevant information of the opponent, yourself or even around the game, then there is obviously no perfect information. This usually creates a sort of necessity to deduce the unknown from what is more or less known, 

Unknown opponent information exists where the statement "My opponent is currently in this state" cannot be immediately answered. Bridge perfectly sets an example as to how unknown opponent information is deduced through bidding and sometimes card play.

Any game that involves drawing from a deck or hidden stock is also unknown information. In this game, any statement about the state of the game as it happens is indeterminate.

Facts about a game that are not explicitly obvious do not count. This type of information is still open and depending on the rule you may be able to ask for it.

Things that might happen

Foresight is an aspect of gameplay that we can consider to be beyond the limit of player information and so does not usually count. After all, much of game strategy is planning ahead, and therefore taking into account possible and probable events.

Dis Co Creator of disco: Canadian football fans - 9 pts, 3 vts
Orgre45: Commitment! - 4 pts
Thick white sauce: Canada be like: - 2 pts
Gary Gravy: Reason number 1,673 why hockey is better than football. - 3 pts
C0W: [Bills:13/Colts:7] This was such a boring game that Mother Nature had to spice it up. - 2 pts
Egghead2: Photograph of a group of citizens affected by SCP-3799.The individuals within this photo are presumed to have been turned into SCP-3799-1. - 0 pts
TheSilhouette: When the bazookas in the game stadium had "accidentally" replaced T-shirts with 100% pure cocaine. - 19 pts

JoshuaKing: When you're cold and want to leave but you're waiting for Volc's game of nobody wants it. - 9 pts, 4 vts

drumset04: "Just another day watching a home Cowboys game" - 4 pts

Ellzie: "We're not leaving until the Red Sox win!" - 6 pts

DudeCats: "Which team are you rooting for?" "The cool one" - 8 pts

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2			2	1	3		2	3	3	3		19
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Somebody once told me...

TechRat: ... there'd be days like these - 5 pts, 2 vts
InfamousCuttleFish: ... he would give me candy if I got in his car and he kept his word! What a nice guy - 9 pts
Thaz: ... that I've got another confession to make I'm your fool Everyone's got their chains to break Holdin' you Were you born to resist, or be abused? Is someone getting THE BESRT THE BEST THE BEST THE BEST... - 8 pts
SSBBHax: ... the world was gonna rule me. - 4 pts
Nomi_girl: ... that if you sneeze with your eyes open then your eyes will pop out! - 7 pts, 5 vts
JXQZ: ... that you had a boyfriend that looked like a girlfriend that I had in February of last year - 5 pts, 3 vts
the LIonESs: SUCK BRICK KID!
-Guy from home alone 2 - 3 pts
Noobsauce: ... that girl was gonna blow me - 7 pts, 3 vts

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3		1		2	1		2			9
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2			1		2	1	1			7
1				1		3				5
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	1	3			3					7

Cmac: But...but..... I don't wanna play that game... BWHAA!! FIN for Flinchin! - 8 pts, 4 vts
Lord Stefano: "Dont make me ask twice" - 4 pts, 3 vts
UndergroundThings: "are you lookin' at my bird?" - 1 pt
Tersr: When senpai notices you in the wrong way - 4 pts, 2 vts
SpaceFart: Smackeral - 16 pts
Pastahead: the weaker fish had enough and BITCH-SLAPPED the bully fish.... - 8 pts, 3 vts
Lesbian_Syphilitic_Spanker: Fin-st of the North Starfish - 4 pts, 2 vts
Xantaxar: BAKA! Why'd you take me to a sushi dinner?! - 2 pts
WhoWhovian: "Why did the shark cross the sea? - For the hallibut" "Cod damnit Barbara, enough with the fish puns!" - 7 pts

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Tersr: The first fish run office sprung a leak - 1 pt
Muush: "This is not what I meant when I said I wanted an ocean view!" - 4 pts
Sparksol: Although fun at first, filling the entire apartment complex with gelatin turned out to be unwise. No one was ready for that much jelly. - 10 pts, 2 3's
lagoticspy: um this isn't exacly what I meant when I asked for an indoor swimming pool. - 7 pts
hiyamate: well, you can't complain god doesn't help with washing up - 2 pts, 2 vts
Grushvak: I know, I know, dolphins are super smart and awesome, but let me tell you, they make awful flatmates. - 5 pts
BearFortress: "no honey of course i turned off the sink" - 10 pts, 1 3
TwoLions: I clogged the toliet again - 2 pts, 1 vt
Ouro Boros: following the "incident" the Aral sea had to be let go. It was a hard worker, but its temper and drowning of coworkers was a bit much. - 3 pts
Poodle Noodles: Man, screw underwater hotels. - 16 pts 
Volc: When they said drowning in paperwork, they might have taken the 'drowning' bit too literally. - 6 pts

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1				3	2	1	3					10
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3		3	2			3	2	3				16
2			1			2	1					6

Jeff Jeff: With this, I can catch every AR in /games. - 6 pts, 3 vts
JoJoBa: /em forgets to turn the cameras on #nopro - 2 pts
Thicc Earth Society: Master Yi cosplay - 13 pts
ham6691: Don't worry... If I see that unicorn again.. I'll get it on tape! - 5 pts 
girlTrex: a pyramid of 17 cameras for when you must see EVERYTHING - 3 pts
Firetitan8: "The members of the Cult of Mechanicus often haze Aspiring Tech Priests by throwing them out of planes with a handful of scrap metal, having to make a landing device before they reach the ground" - 5 pts
Egghead2: Photo of a Skycam - 6 pts, 5 vts
TheSilhouette: How they shot tech comparisons. - 8 pts

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2	1		3	3		1	3			13
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1		1	1	2	1					6
3	2		2	1						8

The Great Necronoodle: terrorpool - 2 pts
fear_town: Right tool, for the right job. - 4 pts, 3 vts
Lethamyr: People hunting for the Pooltergeist UR in the Haunted Billiard Room -10 pts
ham6691: Its ok my brother, I make the 200 IQ conservation of momentum calculations... no way this will fail - 4 pts, 2 vts
Noted: "This game is like golf. Low score wins and you need a hole in one" - 8 pts
TheSilhouette: CNN: "ISIS (Islamic "Striker" Is Smexy) lining in for a "kill shot", while citizens "run" in panic." - 3 pts
jojobo: The English language really needs to be more specific. - 11 pts

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3	2			3		2				10
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1	3		3	1	3					11