RetroAchievements 

RetroAchievements is a website to play retro games like Atari and NES titles on emulators and earn achievements in them. Also newer consoles like N64, PSX and Nintendo DS are supported. The achievements on the site are made by players for players and contain achievements for game progress, finding easter eggs and a lot other creative challenges. The players can show their progress to other users on their profile and also submit highscores and best times of minigames and races to compete with other players to be the best. The number of supported games increases every week and there are special events to make playing the games even more fun. The best thing, it's for free!

A: Did you master the Sonic set on RetroAchievements already?
B: Yeah, I finished the last achievement today.

RetroAchievements by SporyTike January 16, 2020