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currently we just have steam achievements and stats feature, but steam have much more good features, u can see full listed in this link: https://partner.steamgames.com/doc/features
for example steam have it’s own IAP feature that isn’t very hard to implement
or auto matchmaking and p2p network connection for multiplayer games, that don’t need to worry about buying servers
also steam have premade/auto leaderboards which display friendlist ranks
or with inventory service we can add community market items/cosmetics to our games, to give our players sell-able items
more integration with steam features such as: steam overlay – friends leaderboard – inventory service – html surface