It's true that The Legend of Zelda has 25 carryable items (see http://www.zeldadungeon.net/Zelda01-the-legend-of-zelda-item...). But it also has a bunch of other items: hearts, heart containers, fairies, pieces of Triforce, blue and red rupees, the magical clock, possibly other things (this is off the top of my head). That's 32 items, which is I think the count in the article. Of those, at least 18 are classes of things (eg "key", "sword", "potion", "health"). Each class has a unique function (almost -- the wand is arguable). By comparison, half of Doom's items are the same class ("gun"), and most of the others fall into one of the two classes "health" and "armour". I think the OP's point is quite well made here: Zelda, even the first one, made in 1986), puts a huge emphasis on unique items and incorporates them into puzzles.