Which retail innovation first allowed MMO players to purchase virtual items with real money through an official, developer-sanctioned marketplace?

The gaming industry has transformed how virtual economies function, with innovative retail strategies that blur the line between digital and physical marketplaces. In-game purchases and virtual storefronts have become sophisticated retail environments generating billions in revenue. This poll tests your knowledge about a pivotal retail innovation that revolutionized how game developers monetize their virtual worlds and how players interact with digital merchandise.

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Sony's Station Exchange for EverQuest II (2005)
Valve's Steam Community Market (2012)
Second Life's Linden Dollar Exchange (2006)
Blizzard's World of Warcraft Trading Post (2004)