I remember buying the copy of Official Playstation Magazine that had the Metal Gear Solid demo disc just because it had that demo. I'm not even sure I read the magazine. The demo let you play up to finding the DARPA Chief (first 15 minutes or so of the game), and I must've spent hours playing it. That was the only game where I did that.

When San Andreas came out I considered that the epitome of video games, because it was both open world and had a big enough map you could spend a very long time simply exploring it. I don't even think I ever beat that game: I just kept driving around exploring the map.

The last game I bought when it came out was Guitar Hero III because I was really into those games at the time. I was a young engineer with no responsibilities other than coding (ie. no meetings or emails), so I'd spend my days coding and my nights playing Guitar Hero. Good times. How I avoided Repetitive Strain Injury I'll never know.

Probably mobile games was what I'd consider the death knell of "old school" gaming, since that was when the game studios "found their razor blade" and started building microtransactions into as many games as they could. Games ceased to be a thing you simply bought and enjoyed and then became a platform through which the developer tried to extract more and more money from you.