Quake 4 from a few years ago was pretty good as a single player game. I can't even get past the first few areas on the hardest setting. Even on the kids/grandmas setting (what ID used to call "Easy") you had a lot of play-time and the baddies were often very challenging to defeat.
Never played multiplayer online that much as our internet has always been to poor, but I have noticed that newer generation games are getting way too easy:
Tomb raider 1-5:
Mind-wrenching and hair-pulling at times, required serious thought.
I'm going to pretend it doesn't exist
Engine is pretty cool but the puzzles are WAY too simple and even I cleared the game with only a handful of deaths. Way too short as well.
I think the market has changed a fair bit, which to an extent explains the problems we get. "Cool people" never used to play games, but they've become more mainstream over the last few years, and thus games developers have the opportunity to make games that appeal to everyone (and thus make more money by selling more copies). This has logically led to dumbing down and more of an emphasis on online play, as it allows you to be "sociable" and thus it's more acceptable to the mainstream.