Growing up playing the likes of Sonic, Mario Kart, StarFox and even some of the more un-known Sega Megadrive games (such as the ever brilliant The Haunting,) and then playing the likes of CoD now, you can see how far downhill games are actually going.
The last great game I can remember playing, that was both fun and challenging, was Future Cop on the PS1, I remember sitting there with my cousin and the pair of us just trying to get past one part of a level, and it wasn't down to the game not letting us do something, it was simpy down to the skill involved in playing the game. Most of the older PS1 games are the same, with Tekken 3 being a major example, so much time spent just trying to unlock the Doc, beating Ogre and true Ogre over and over again, looking through magazines for cheat guides in order to actually make the game a little easier, when now, you can just change the difficulty and all those cheats are in the game already, just waiting for you, there is simply no challenge in gaming anymore.
Even modern greats like RDR leave something to be desired, that comes across to me as a wild west simulator, even though it is enjoyable, it comes nowhere near to the amount of fun you could have just putting the first Crash Bandicoot on again, or the first Rayman, or Sonic, Mario Bros. World, Donkey Kong 64, Banjo Kazooie, Jack and Daxter ect, all games that kept the challenge in them but were also fun to play.
Gaming needs to get away from trying to get the best out of the hardware and start moving towards the fun factor again, it's been missing for far to long.