Would not say mastered, but got consistently good at BF2. K/D of 3.1 at around 900 hours of play time. Played 3,546 rounds, came first in 697, 2nd in 381 and 3rd in 259, so top 3 in roughly 40% of games played.
Pretty solid at Elder Scrolls online, completed hard content like Veteran Maelstrom Arena multiple times, HM trials and so on.
Only 100% handful of games. Skyrim, Dragon Quest, Assassin creed Origins / odyssey etc