Now, it has followed that up by beating expectations at the North American box office in its first weekend on release.
The film made $30.2m (£24.9m) over the weekend, well above predictions of between $17m-$20m (£14m-£16.5m).
"Word-of-mouth is through the roof," said Jim Orr from its studio Universal.
That put M3GAN second in the US and Canada box office chart behind Avatar: The Way of Water, which took another $45m (£37m) as it became the seventh highest-grossing movie in history.