NetHack is probably the most played and famous roguelike currently played, featuring an extremely complex item system: "the dev team thinks of everything." Version 3.4.3 dates back to 2003 and runs on pretty much any OS.
NetHack is a open source roguelike game originally published in 1987. One of the most distinctive features is its extensive item system; items can behave differently based on the character's status, the item's blessed/uncursed/cursed (BUC) status, the player's form or the surroundings. It is often said that the dev team thinks of everything.