user: Question: When did Masthead Studios release their 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 "Developer(s)" = 'Masthead Studios';