Note: NES = Nintendo Entertainment System; SNES = Super NES. Also, whatever I talk about here probably applies to other consoles like SNES and the SEGA Genesis but NES is most influential in my mind and the true milestone in gaming history.
And when I say hard, I mean hard, they got you yelling at the screen in jibberish and obscenities when you lose and when you beat that boss that was only like the 3rd in the game but so hard for some annoying power he had or what not. My favorite moment of rage is when its some small enemy that is annoying for one reason or another be it that they're small or frequent like bats and birds (damn those bats/birds to hell!) and when you kill one, you flip out on it to show your dominance; reminds me of the story of the little man who slapped the wrestler on his bald head and the wrestler proceeded to pound the crap out of the little man who continued to laugh while the wrestler wasted energy in raging and hurting someone significantly weaker than him. Yeah, that makes me look bad but at least I got that damn bat right?
Regardless, they were some of the most fun games I have ever played, even more than some 3D games of modern times. They had this appeal to them that can't be captured. In a way, they were more real than modern games. For example, one really annoying trait of a lot of NES games was no save option. When you had a password option, it was like 20 characters to put in ranging from lower/upper case characters to numbers and symbols and you wonder how much better the gameplay could have improved than it already had if they had used the extra memory they spent on the password system for the gameplay instead. Anyways, in real life, you don't get to start from the last save point or even input a password but I doubt most kids would bother with that unless it was a particularly long game. Multiple lives is an issue too but for games where you die one hit deaths, that balances it out as there are many things human can survive in real life. Beat surviving hundreds of bullets to the head with bandages.
Another thing that is quite appealing is the music. There's something about 8-bit tunes that are 30 some seconds long that keep looping which keeps you going. Its like a jingle from some catchy commercial or the introduction to your favorite Saturday morning cartoon. There also aren't a lot of long lyrics, usually incomprehensible, which need to be remembered to hum along with it. Its particularly interesting to note that good NES music kept you going, especially if its a particularly hard game where you die a lot because you'll hear more of it when you come back. Imagine 8-bit Eye of the Tiger, except not just for training. They also make cool ringtones and alarms; thank God for the man who made available the tunes for Mega Man 1-6 on the Android market.
Also, a lot of games on the older systems had a lot of freedom. I don't mean lack of linearity though some games did have that, I mean freedom for the imagination. These games did come with manuals which gave stories and characters and even controls (will get to that in a bit) but who reads manuals? I do but I like to think I'm part of the minority. When they do, its still just text and some pictures of the game but they don't always help in actually getting through the game and there is where the adventure was. You could spend hours playing the game and still be less than half way through. Nowadays, you're led along like its a movie which has its own appeal but its not the same adventure I think. Tutorials are quite necessary now also, you drop straight into most any FPS without some onscreen help or tutorials, you might be at the first stage for a long time.
Finally, the controller. It had a D-pad, a start button, a select button, and 2 "action" buttons, that's it. There was a beauty in such a simple design for such difficult games. Mastering a game with so many obstacles and jumps was amazing and noteworthy. It reminds me of a language almost with limited letters which in the proper order can express so much. You didn't need to keep track of 20 hotkeys on a keyboard or 10 buttons with 2 joysticks on a controller though again that has its own difficulties and enjoyment. Nevertheless, that is all you had to defeat the final boss and his 20 fireballs or whatever.
It is a shame though that many people today don't appreciate some of the really good games of that day or wouldn't care to go back and play them for even a while or even on an emulator where the comforts of modern gaming are provided. I think some games definitely should be played again to see the roots of modern games, especially those games which still continue on today in remakes and sequels and prequels and what not on modern systems. It adds another level of awesomeness to the experience I think and to the story of the characters you play now. Its like people who listen to modern music. I don't like a lot of modern music but some people love it all but I think they need to check out old tunes to see how music really evolved because even some pop artists have probably listened to more classics than we think. Books too are a good example as something like Catch-22 or Count of Monte Cristo never get old and show where some ideas originated.
There are many other points I can get into as well as expand on many of the points I got to here but you get my drift. I would suggest checking out some of these games in your spare time if you have any. Even if you can't play, I would suggest checking out youtube videos of playthrough because while they're not the same, it has some of the visual benefits mentioned. Again, if you have time, don't give up your day job or family for it.
BTW, I haven't quite talking about serious topics, anyone who's read my first post should know I said I would talk about whatever. Also, I will discuss some NES games as soon as I beat them. That's another thing I like, they have a lot of secrets which gives a lot of replay value. It is after an adventure, even non-adventure games.