A Concept of Life, a game of development and the eventual inevitable demise, and the afterlife.
The game world is a somewhat tile based 2d sidescrolling platformer, the game takes place in a randomly generated world, where the initial area is a big valley with two concurring civilisation's in each side of the valley, both with two different concepts about life, these are randomly chosen between, life is about work, art, adventures/thrill, love, war, god, and no matter what, theese two civilisations are at war, spreaded throughout the world is remnants of an eldritch civilisation, for example a brigde crossing the valley bottom, wich infact is a bottomless lake, pit, volcano, etc. The world would be pretty big and random, taking atleast a whole game to reach either sides of the valley, and beyond would be an infinite desolate waste of horrors. The game would be pretty thematic, the higher you go, the more windy it gets(untill the point where there is no athmosphere at all) and the more spacy and light the music gets, the lower you go, the more dark and scary everything goes, and eventually you reach the top of evil, where it just corsses into depraved weirdness. So going up you will find the peaks of the two past-everest high mountains forming the valley, and then the occasional flying city/floating isle full of eldritch remains, eventually you reach space wich requires proper equipment to explore, and going far enough out you will find hidden fun stuff.
The player starts out as a little weak migdet, a member of a minor sub-culture of one of the greater two empires. You cant do much, you are easily hurt, cannot endure much and you are easily offended and gives easily into pain. All the things you do have some effect on your soul, like making love would give love to your soul, and if you really want to make family, the content of your life would eventually be the love to your partner. The player is always born with some kind of personality, fame seeking, thrill seeking, adventurous, creative, inventing, warrrior, etc. And corresponding to your personality different actions gives you satifaction. Everything you do will have some impact on things, like if you dig a hole, another migdet might fall into that hole and die from starvation, if you plant that tree over htere, there might be a young couple kissing there, etc. But as you play, you eventually get stronger in some kind of way, maybe you make lots of money on crafting, owning a mine, maybe fame from art, or your tour down the west peak on a freaking plank, maybe accomplishment from that statue you made, your wife. Or maybe you will get really strong from mining or fighting, or really high and atheltic from jumping around on peaks. Maybe you would be born cursed to the gods, and forced to run into the wasteland outside the valley, and confront your ancestors ghosts, eldritch horrors, etc. Or maybe you would wander the underworld in seek of gold to satisfy your never ending hunger for precious stuff. Or maybe born an abomination or raised in an evil cannibal religion of dark magics. But some time, owning a big castle, having 47 wifes and eating the remains of the eastern empire's king or not, you will face death, maybe he will knock on your door one day when you are an old guy sitting in a rocking chair, or maybe Karma pays back and all the underworld creature's you have slain comes back to take you with them. And you will have to face with your final result, your afterlife, a happy and accomplished soul will be lighter than air and drift into the heavens, while a more heavy soul will fall into the underworld, forever, untill stuck in your rotting corpus of your past life, maybe you never really did something, and will either haunt the world, in search of what you never found while being alive, or maybe just get another chance.
The game itself would be a tile based sidescroller, with slopes and blocks, things would be physics simulated and stuff breaking would become debris, when there are not particles enough to make a block, it will just slowly decay, to prevent slowdown. Everything, including the player itself, would be able to be damaged to the point of gibbing, living things would be able to live on with their wounds, unlike most games where loosing an arm = dead, and YES that would allow for stuff such as playing basket with the severed head of your local mayor, or eating the severred butt of a cow or whatever, lets just say that slaughtering animals, and people would be realistic, to the point where anatomical simulation comes in.
Sorry i am a bit very tired, but what i want to tell about is my idea of a sidescrolling 2d pixely game where you develop from being a featureless migdet into whatever else, then facing death. All that happening in a rich random world full of stuff like underworld jungles, randomly generated undead, open ended and very dynamic magic and all that, with simulation of anatomy, physics, social stuff, chemistry, particles etc. etc. etc.