Development of Uncharted 4 began in 2011, soon after the release of Uncharted 3. It was led by creative director Amy Hennig and game director Justin Richmond. Development was hampered in 2014 due to Hennig and Richmond's departure from Naughty Dog; they were replaced by Neil Druckmann and Bruce Straley. The team sought to incorporate elements of open-world gameplay, with larger levels to encourage free-roaming exploration and combat. The relationship between Nathan and Elena was central, and Naughty Dog attempted to humanize them more than in previous games. A Thief's End was released in May 2016 for the PlayStation 4. It was the first Naughty Dog game developed specifically for the PlayStation 4. The team took advantage of the hardware to process larger dynamic environments.