They're just using a 5-star scale which means a 3/5 will translate to a 60. This is a flaw with Metacritic as much as Eurogamer. This is what Eurogamer explains is their criteria for a 3-star game:
3 Star reviews will range from lukewarm to even mostly positive, for the wide variety of games that just lack that next gear up. It might be a polished, well-functioning effort that doesn't do anything particularly interesting, a slightly uninspired year for a mostly great annualised series, or even a brilliant concept that ends up with mixed results in practice. Crucially, 3 stars should be seen as a middling, mixed, or positive-leaning review - it is not a negative or "bad" review.
This is the problem with their scale, 3 stars ranges from "lukewarm" to "mostly positive". If they used a 10-point scale like a normal outlet, they could give the "mostly positive game" something in the high 70s while the lukewarm game would be at 60.