Best case, the players are co-located in a city or country, and they'll benefit from data center locality.

Worst case, they're not co-located, and one participant has good latency, and the other doesn't. This is equivalent to the "deploy the backend in a single server/datacenter" approach.

Aside from the data locality, I still find the programming model (a globally-unique and addressable single-threaded class instance) to be quite nice, and would want to emulate it even without the Cloudflare edge magic.

Some games have regions and you only see players in the same region. For example, a “Europe” region. If you’re in the US and you connect to the Europe region, you know that you should expect some lag.

And it seems like that would work just as well with durable objects.

In practice you’re most likely to be collaborating with other folks on your school project group, work team, close family, etc. Sure there are exceptions, but generally speaking picking a service location near your first group member ensures low latency for them (and they’re probably most engaged), and is likely to have lowish latency for everyone else.

On the flip side, picking US-East-1 gives okayish latency to folks near that, and nobody else.