Will Big Walk’s 1m+ sales usher in a ‘co-op only’ game era?

The excerpts provided don't contain sufficient factual information to construct a reliable synthesis. The first source offers only a subjective descriptor ("one of the best puzzle games"), while the second consists of fragment headers without substantive details about Big Walk's sales figures, game mechanics, market impact, or any analysis of industry trends.

To write an accurate synthesis, I would need excerpts containing:

- Confirmed sales numbers or player counts

- Concrete details about Big Walk's design (co-op requirements, gameplay loop)

- Actual industry analysis or developer commentary on why it succeeded

- Context from multiple outlets about whether this signals a broader trend

Without these facts, I cannot fulfill the assignment responsibly.