RetroAchievements.org is described as 'Were you the greatest in your day at Mega Drive or SNES games? Wanna prove it? Use our modified emulators and you will be awarded achievements as you play! Your progress will be tracked so you can compete with your friends to complete all your favourite classics to 100%'. There are four alternatives to RetroAchievements.org for a variety of platforms, including Online / Web-based, Windows, Mac, Windows Phone and Snapcraft. The best alternative is Steam, which is free. Other great apps like RetroAchievements.org are GOG GALAXY (Free), FreeToGame (Free) and ScienceGameCenter (Free).
The gaming Client designed for a convenient purchasing, playing and updating DRM-free games, as well as an online play between gaming platforms, GOG GALAXY is also built with optionality in mind, and a belief that you should own the games you buy
FreeToGame is a gaming platform that provides access to the best free-to-play games and MMO Games while rewarding gamers with free premium in-game loot, special offers and exclusive perks at no cost to the user!