Mobile cloud gaming requires a very low end-to-end latency. Edge computing significantly reduces network latency. However, in mobility scenarios, the user will frequently move out of the edge server's coverage area, requiring frequent migration of the game instance. This paper presents Talaria, an in-engine content synchronisation solution for unnoticeable game instance migration between edge servers. Talaria creates a minimal instance with content immediately relevant to the game experience, allowing the client to switch servers in a minimal amount of time. The remaining content is then synchronised according to priority until the game's state is coherent between both instances. Our implementation of Talaria as a Unity engine plugin reduces the game's downtime by 61% compared to one-off server migration, with an average latency below 25 ms for the server migration, and 87 ms for the entire game synchronisation.