The ability to specify the read and write sets succinctly motivates our model of state partitioning and replication.
There are two kinds of game state: immutable and mutable state. Immutable state is globally replicated (i.e., every node has a copy). We refer to the collection of mutable objects as the global object store. Each object in the global object store has a primary (authoritative) copy that resides on exactly a single node, and a set of secondary replicas (which we will just call replicas in this paper) that reside on other nodes and are kept synchronized with the primary in an application dependent manner.4
Each node maintains its own local object store which is a collection of primaries and replicas of different objects. An object has an area-of-interest, a selective filter which describes the objects it is interested in, such as a visible bounding box (i.e., this is the object's potential read or write set). In addition to primaries, a node maintains replicas that are within the union of its primaries' area-of-interest in its object store.