user: Question: When did Riot Games release their 3D MOBA game?
Columns: ['Developer(s)', 'Release date', 'Required OS', 'Genre', 'Type']
Types: ['text', 'text', 'text', 'text', 'text']
Sample row: ['Robot Entertainment , Gas Powered Games', 'August 16, 2011', 'Windows', 'MMORTS', '3D']
SQL:

assistant: SELECT "Release date" FROM "Table" WHERE "Type" = '3D' AND "Genre" = 'MOBA' AND "Developer(s)" = 'Riot Games';