As Google has recently made major changes to Firebase, they've released a service called Firebase Cloud Messaging, or FCM. I was wondering, could this work as a backend for a real time game between two players, as a replacement to a protocol like TCP or UDP? For example, a multiplayer game controlled by a game server with other player's position updates multiple times a second. I see that it can transfer 4kb of data per packet, and since it's hosted by Google I would think connection time would definitely be quick; however, Google doesn't advertise it as a game backend, but instead a messaging system suitable for applications like IM.
Basically, what I'm asking is, compared to protocols like TCP and UDP, how does FCM compare in terms of:
- Reliability
- Speed
- Amount of traffic it can handle
- Is data sequential like TCP, or "random" order like UDP?
And in the long run could it stand up to support constant communication between a game in server?