Retro gaming for most people starts with the first machine they owned or played.
Mine would be the atari 2600 game machine and space invaders/pacman/centipede/battlezone arcade machines (34 yrs old). So basically I grew up at the start of the home video game industry and at the start of the switch from pinball to video arcade machines. There is a whole other generation before me that retro means pinball machines.
The funny thing is that each generation of game type from the atari 2600 to the present day interests me. I find it funny how people that liked the old systems cant stand the new ones. Done get me wrong there is alot of crap released today on the PC, but there are some excelent titles coming out also. There was also alot of crap released with the old systems but we only remember what we liked.
I also like to split the retro scene into 2 very different categories, the people who emulate and the ones who buy the old hardware and run the games as they were meant to be (full frame rate, exact audio sound etc). I think the people in the retro scene using real hardware is dropping like a rock, everything is emulation on the PC these days.
The reason I like the retro gaming scene is because there are games that will never be redone in todays system. Back in the day 1 or 2 people would create a game that they would like to play and release it. You had alot of inovation going on since 1 person controlled the whole game from start to finish, anything done today is by commitee and ends up more of a mishmash of features then a coherent playable game. Still the few games today that I love could never have been done in the past by 1 or 2 people even with the current hardware, too much content.
The demo scene like I seen in the c64 era is dead because of a few things. One is that nobody programs direct to the hardware anymore, and few have the deep knowledge of the hardware to even try it. That and todays computers can basically do anything, back in the day people could make the c64 and the amiga do something nobody thaught possible.. well the new hardware makes just about anything possible and its alot harder to impress somebody.
I think gaming is like fashion whats old will eventually become new again. The games you liked on the amiga are coming back in the form of GBA roms that a new generation is falling in love with.