That's a good one vudu, but your all missing the point.
Let me break this down Topically:
Boozers
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Let's say there was a game with every known drinking game ever. From card games, to games that you make up simply to get drunk. This game could act like a freaking cookbook of sorts for all your drunken parties. If you're tired of playing kings, then check what else is out there within the game. And if you don't have the proper utensils to play, then play it the game with the REV NRC.
Stoners
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Make a game thats insanely funny. You could do something really complex, or you can even do something as simple as Mario Party. However, most things in life that are funny aren't stupid, instead, they are cleverly stupid.
It's hard to make a game for stoners with out blatantly putting pot in the game. Although, since most stoners enjoy videogames already, then you could skip this group all together.
Shroomers
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This would be by far the greatest game to come out of this "videogames for drug users" topic. Since they are tripping balls already, all you would have to do is accent that buzz. This leaves you with a huge amount of freedom, similiar to a painter with a blank canvas.
I remember Nemo talking about a Super Mario game where Mario eats mushrooms, and instead of growing bigger, the world changes. That's a great idea. They shouldn't incooperate Mario into it, but a 2-D scroller where the edible content changes the world would be awesome.
Imagine this little dude strolling, having a good time, till along comes an item. This item changes the clouds purple and the sun blue. The music turns all trancy and as the kick drum hits, the clouds shake. Now this dude continues, minding his own business when all the sudden the floor cracks, a hole opens. You're falling. The background goes all crazy as the music intensifies. What at first was a smooth mix of melodic jazz turns into crazy intense guitar and drum solos. The music - visual combination could basically make the game.
Ok, now imagine this. As you reach the end of the level, the music goes silent and the TV goes black. All you can see is the dude's eyes as they blink. A lighted dot, with light the ripples from it appears. It moves all around as you chase, till finally you grab it. the light brightens and theres this HUGE F***IN' MONSTER standing a foot away from you. The monster eats the background and is about to eat the ground you stand on! You start running back, this time though, the backround keeps changing as the monster eats the scenery. A bunch of different locales appear as the monster eats the background and the ground before you.....I don't know how it would end, but the music would be intense!
Like Mario, the goal would be to get to the end of the level.
That's bad ass. It could be like Milkdrop (check that visualizer out, it's crazy sober....I don't know anybody that's check it out intoxicated), except a living breathing world.
The best part is, you have NO IDEA what to expect and that, like Family Guy, is what could make it so great.