Below is an context that describes a sql query, paired with an question that provides further information. Write an answer that appropriately completes the request.  # noqa: E501
### Context:
CREATE TABLE table_name_91 (required_os VARCHAR, developer_s_ VARCHAR)
### Question:
What was the minimum operating system required by Stunlock Studios' game?
### Answer:
SELECT required_os FROM table_name_91 WHERE developer_s_ = "stunlock studios"