Day 24: Most Complicated RPG Owned
Complicated is a difficult term to define and there are several ways to interpret this. D&D 3.5 probably has the most complex ruleset in terms of sheer number of bits and pieces. AD&D is the least coherent, because its fairly rules-light system is a set of one-off rules cobbled together in rather arbitrary order, split unhelpfully between different books, and with no attempt at streamlining them into something more unified. FATE isn't an especially intricate system, but I have never managed to get my head round how to combine the narrative unfolding before me, the things I or the players want to try and achieve, and the actual mechanics.
I suppose Deathwatch is another contender here because it has so many bits. Each skill has specific definitions for several ways it can be used and how to do so. Weapons have individual rules and effects. Spells are esoteric magic, so require rules-per-spell. Even the basic starting Space Marine has to bear in mind a couple of dozen special abilities, genetic enhancements and bits of tech that provide modifiers, immunities, rerolls and exceptions. These aren't overwhelming once you're playing, but it is a lot of stuff to bear in mind.