Anthropomorphism: the apple moves like the snake, man was made to the image of god and so on.
Apocalypticism: the game just ends after a few moves without notice.
Asceticism: the game ends if you eat the apple, you are supposed to be like a faquir.
Capitalism: you start the game with 50, spend 10 each apple you eat - when you are broke you can't afford the apple.
Casualism: I had to Google this one, the screen just flashes with random squares.
Conservatism: just the plain old snakes game.
Determinism: the snake just moves by itself and you are unable to control the game - your destiny was set in stone the moment you were born.
Dualism: you can control the snake body with the regular controls, and you can move the snake mind with your mind. My mind is too weak so I was unable to move the snake mind.
Existentialism: you move the snake in a dark screen - after reading the wikipedia I guess the joke has to do with freedom in a meaningless world.
Holism: the whole screen moves with the snake (makes it very hard to get the apples in the corners)
Idealism: imagine you are playing a game of snakes
Monism: your play is not restrained by the walls - after reading it I guess the joke is about you being made of the same substance of god or something like that
Narcissism: when you finish the game it sends an email to the creator about how much you love his work.
Nihilism: just a black screen, no snake, no apples - nothing in the world really exists.
Optimism: you see apples everywhere but looks like they are not nourishing because the snake doesn't grow.
Pessimism: the play field is smaller and the apples appear outside of the walls where you are unable to reach.
Positivism: you see only a narrow part of the play field, I guess the joke is that you are unable to know the universe because our senses are limited.
Post-apocalypticism: no apples, you just move through a scrambled play field.
Romanticism: every time you eat an apple you see a cheeky statement like "food tastes like ashes when I'm not sharing it with you".
Stoicism: like a plain old snake game but you don't die when you hit the walls or yourself - after reading the wikipedia article I guess the joke is that virtue is sufficient for happiness, so the sage is immune to misfortune.
Utilitarianism: you have only two very narrow paths, one with 5 apples and other with one apple. If you take the one with more apples you win, otherwise you loose.