Quote from: NYTFLYRI will make a comment that any game can be casual gamer friendly with the right GM...

I've made that assertion several times - the idea that Vampire, or GURPS, or D&D 3.x are friendly to casual gamers is the result of hard-working GMs that actually make it easier for the less-than-hardcore gamers to game. I do it myself; there's nothing really inherently wrong with it, other than it does nothing to address the issue of the accessibility of games.

Most everyone has listed the games I would have (TFOS, Gamma World, Basic D&D) although I would hesitate to put AD&D of any flavor or CP2020 on the list. AD&D was pretty complex if you actually read the DMG (which I never did, but hey I was 12). CP2020 kind of violates one of my notions for "accessibility" because it is rooted in a pretty narrow slice of the science-fiction genre. The flip-side of that is that the tropes of that genre are pretty mainstream, what with The Matrix and even non-CP movies like Swordfish. Something like Star Frontiers is a good choice because it's simple and draws on much broader science fiction concepts that most people will easily identify with.

Quote from: Aegyptopretty much everybody knows everything that matters about the setting.

That's a big plus for any game.

My votes

World of Darkness- Simple rules, and if you can fill out a lottery ticket you can make a character. Also none of the complicated meta-setting from Vampire, Werewolf etc. It's like Scooby-Doo, but serious

WHFRP - Easy enough Character creation, easy to understand percentile system.

Castles & Crusades - Like D&D but even easier to play.

I think that it is difficult for noncasual gamers to know what casual gamers would be interested in. I respectfully submit that 3.X aint it. I bought the books after a long hiatus from gaming with the idea of starting up a casual game- I stepped away almost instantly. It might seem simple to you, but to someone who has never gamed before or has only done so a little bit I can't imagine that it would.