Tetris and Doom. i.e: The somewhat difficult ones

I think we should speak of 'core' games instead of 'hardcore' games unless we mean those really hardcore games. War simulators and such, you know. That's hardcore. Call of Duty definitely isn't casual, though it has some casual approach. But it's also far from hardcore, it's too simple for that. And then there's games that are neither casual nor core but somewhere between. I consider Mario games to be in this category, they're meant for both groups of players.

@O-D-C: You don't know what Commander Keen is or you don't know which category it fits in? If it's the former, shame on you, if it's the latter, I don't care.

Only Doom is hardcore.

I find the wikipedia definition to reflect my perception of what is casual:

A casual game is a video game or online game targeted at or used by a mass audience of casual gamers. Casual games can have any type of gameplay, and fit in any genre. They are typically distinguished by their simple rules and lack of commitment required in contrast to more complex hardcore games.

Most of the games in your list have very simple rules and arent particularly emotionally or intellectually engaging (lack of commitment). So I think most are casual.

I think its more about the complexity of the gameplay/story than the difficulty to achieve good score. In my opinion you can be a hardcore tetris player but that doesnt make tetris an hardcore game. What do you think?

Hardcore games are games that came out before 1995, except for bullet hell games, indie games, and Bejeweled 2.

Story has nothing to do with it.  Any 2-D platformer is more hardcore than Heavy Rain or Metal Gear Solid 4.

Why not? I think an engaging story will help make a game hardcore. I think that because having an engaging story makes a game more complex. But, I dont mean that the story by itself will make a game hardcore. Now, can you explain why a 2D platformer is more hardcore than metal gear solid 4?

Where are you taking your definition from? At least why do you think that?

It was right about 1995 when every game genre got super-easier for a couple reasons.

3-D replacing 2-D: 3-D games are always easier than 2-D games.  You can move in 360 directions instead of 4.  To make up for this, they take out the precision of crazy jumps.  There are jumps in Super Mario Bros. 1 that are harder than any 3-D game's jumps.  Same goes for shooters.  Games like Halo replaced games like Contra and Metal Slug (although the first Doom and Quake games were hard as hell).

Cutscenes changing the focus to story: now games have stories with endings.  So they want you to finish the whole game and get to the end, so you can see the cliffhanger ending, so you want to buy the sequel to finish the story.  Now it's in their best interest to make the game easy enough to beat.  Back in the day games wouldn't even have endings.  Sometimes they'd just say "CONGRATULATIONS" or "THANKS FOR PLAYING!" or "A WINNER IS YOU!"

There was also an increase in save points, and people have stopped using lives and continues.  Back in the day, if you couldn't beat a game in one sitting, you couldn't beat a game.

I threw in bullet hell games because they're all impossible, indie games because they can do whatever they want and make some crazy hardcore stuff without giant publishers breathing down their necks to throw in aliens, nazis, save points, naked chicks, and cliffhanger endings, and Bejeweled 2 because of that guy who played it for 3 years straight and broke the scoreboard.