question

Firstly, as this thread -- https://community.playfab.com/questions/24571/should-i-have-to-use-photonunet-or-something-else.html says. The question that whether you need dedicated sever to multiplayer matches, or if you can just use Cloud Script. It comes down to whether your games follow a synchronous or asynchronous multiplayer model. We can find such description about the differences between them, “synchronous multiplayer is when both players have to be connected at the same time to be able to play together; and asynchronous multiplayer is when player actions are stored somewhere in a database and other players can see those actions sometime later.” According to your description, the game is more like the synchronous game, because the game has a time limit -- 15s. Please correct me if I misunderstand. If what I understand is right. We would suggest you use PlayFab Multiplayer.

>> The question, is this a viable soultion? Can we use TitleData to read and write, from multiple games that are being played. Does this approach scale, or will be run into some kind of inconsistency issues where multiple players and game fight to read and write to the TitleData at the same time?

No matter it’s a synchronous model or asynchronous multiplayer model. We would both not suggest using TitleData to store the state of the current game. As this thread says -- https://community.playfab.com/questions/10445/using-titledata-for-world-stats.html, TitleData should never be written to as a result of a player action, as it is a sharded and cached resource. If you have a TitleData key with some data in it, when you update the value for that key, there's a short period while that data is updated in all the shards. During that period, queries to the data may get either the old or new values, depending on the shard the caller hits. Also, attempting to write to Title Data too frequently will simply fail.

[Edited] For the synchronous game, you can cache the data in the server directly. [Whether using Server or Client APIs, we do not recommend using TitleData in such game models. Please avoid using any player-generated action to trigger the update of TitleData. For example, if you have multiple sessions running with different players, that’s going to cause serious issues. In general, the only time TitleData should be used is for global static data that is updated by the developer. It would be better to use an Entity Group for the session and save the data to an Entity Object (assuming it’s a small amount of data) or an Entity File.]

>> Is this an approach to have a simple lobby system, or should be look into having a seprate game server that runs the games and manages the lobby, and players joining a game in a tournament system?

PlayFab has provided a Matchmaking feature that can integrate with MutiplayerServer directly. Please check the docs for more details.

In addition, PlayFab Multiplayer Server is designed to provide the server sessions, we suggest controlling the running time of a session to one hour. So PlayFab Multiplayer Server is more suitable for the game server, but not suitable for a persistent server, may not suitable for the lobby server. So you may need to host a lobby system on the separate server. PlayFab provides the multiple multiplayer and matchmaking APIs that you use in the clients and lobby server. Some of them can be used for management.

Besides, there are many threads discussed the multiplayer games in the forum. Please feel free to search for them in your need.