Should we capitalize Prisoner's Dilemma and when?

Question

Prisoner's Dilemma is a game used to study both social and economic research. You can read more on it on Wikipidia or in Stanford Encyclopedia of Philosophy.

Interestingly, it seems that either:

1. These two sources are not consistent in how they spell it
2. They change spelling depending on context in a way I do not grasp

For instance on Wikipedia we have

The prisoner's dilemma is a standard example of a game [...]

and then

Prisoner's Dilemma tournaments have been held [...]

or

The structure of the traditional Prisoner's Dilemma can be generalized [...]

Similarly in Stanford Encyclopedia of Philosophy we have:

A closely related view is that the prisoner's dilemma game [...]

and then

[...] take the Prisoner's Dilemma to say something important [...]

or

[...] story suggests that the Prisoner's Dilemma also occupies [...]

It seems that on Wikipedia lower case spelling dominates, while in in Stanford Encyclopedia of Philosophy both versions are used interchangeably.

I would expect it might be correct to use upper case spelling for games matching the definition or for the original version of the game and lower case for variations on it or when more general sense is meant.

That is, we can write

In Golden Balls contestants are presented with prisoner's dilemma

because we mean type of situation in general.

And we can write

This game is a proper instance of Prisoner's Dilemma

meaning that this games matches the definition the specific Prisoner's Dilemma.

However, the abovementioned examples do not seem to comply understanding nor to any other that I could see.

So do these two source spell Prisoner's Dilemma correctly?

And how should we spell it?

Answer 1

A proprietorial, commercial game such as Scrabble or Cludo, needs capitals. For how long it legally needs capitals depends on copyright law; how long idiomatically or socially needs capitals depends on who is asked…

A traditional game such as chess or draughts or checkers doesn't strictly need capitals, but no-one's going to complain if capitals are used through personal preference.