I am sorely lacking in Atari. I would've had one if my grandparents hadn't thrown out my dad's 2600 when they were cleaning out their attic.
I'm only a little older than Saturn and PlayStation (based on their Japanese release dates). I get what you mean though. It's definitely weird when you realize that there are adults that have never experienced the things that were integral aspects of your own childhood. I have cousins who've never used a VCR, meanwhile I still have the one our grandfather bought me in the late 90s.
I think it's really impressive what the community has done with Super Smash Bros. Brawl. Project+ is basically the current "flagship" modpack. It builds on Legacy TE (which is built off Project M), so there's loads of new content and more Melee-like gameplay.
Another Brawl mod I like is Brawl -. Its main thing is that it balances the game by making everyone's movesets overpowered.
Changing genre completely, I really like the Gay Awakening and Gay Fates mods for Fire Emblem: Awakening and Fire Emblem: Fates. The main thing the mods do is add new romantic and platonic supports to the game. The focus is, as the name implies, on adding gay and lesbian content, but it also adds straight content to a lesser degree (like for the characters that can only support with Robin or Corrin).