The Photon Server SDK includes several applications that should provide a good starting point for your own development. What each SDK does and for which game-style it might be a useful basis is described below.
The Load Balancing Application is more or less what we run in the Photon Cloud. It actually consists of two applications: The Master Server and a Game Server which could be run several times.
The Load Balancing application extends Lite in Photon 3 and Hive in Photon 4 but changes a few rules in both cases. As example: Rooms must be either created or joined. Joining randomly is supported and the Master server has a "Lobby" which lists available rooms. All room listing is only done on the Master.
In the Photon Cloud, we run a variant of the Load Balancing application which adds "Virtual Apps" with AppIds.
The MMO Demo Application is a good solution for games where all players share a large world. It provides interest management and the most common base classes for items, actors, properties, and more.
Games with a shared world contain more game-specific logic on the server side typically, so this application should be understood as a sound starting point.
Implements the basic framework for room based games where a small number of players interact, independently from anyone else. In Lite, each room reflects a game (or match) and is identified by its name. Anyone can join and leave any room but only one of them. Clients in a room get an ID and raise events to send data to the others. Properties can be set for rooms and players to make some values available for everyone joining.
The idea is that games that don't require server logic (scoring, etc) can be built with Lite "as is". On the other hand, the Room class in Lite is easy to understand and a good entry point to customize the server logic.
The Lite Application is easily the most often referenced application, used as basis by more complicated projects. Matchmaking could group players in rooms, depending on your game's requirements.