Day 24 question - Most Complicated RPG Owned
Let’s say in core rules rather than overall. I do, after all, own GURPS.
Shadowrun was a pioneer in dice pools and counting successes. A lovely simple little system. But then it added a complex magic system with its own rules in two main varieties (with more in later books) and a complex cyber-decking system with its own rules and subspecies for every Tolkien-y race and more cybergear than Cyberpunk 2020 itself in the basic rules and multistat weapons and special rules for vehicles and Physical Adepts and other kinds of Adepts and... It gave you a lot of options, maybe more than needed, and a lot of gamers really like that, but to me a whole lot of them felt like they could have streamlined.
Most unnecessarily complicated RPG? MERP.