It’s actually the Japanese version of MapleStory that first had the “Gachapon ticket” in 2004, which gave random in game items and cost real money. (While it seems to have been ported to other versions later on, I can’t figure out when that happened). ZT Online is definitely closer to the modern loot box model. While they also didn’t have loot box unique items, they had the model where you used keys to open chests bought with real money. Additionally enemies didn’t drop items in the game, instead it was a combination of buying materials and smithing. This apparently made gambling with keys to get items directly very compelling in comparison. Opening a chest was also rigged in a way where a wheel span on items you could get, but the appearance rate of valuable items was more common than the rate at which you would actually land on them.

Here’s an article written on the game in 2007: https://forums.mmorpg.com/discussion/161383/the-dark-side-of...