How exactly does one draw out a use cases diagram when everything is automated? Here is an example with a request I got:
"Make a modification that resets a game server to a certain map or switches gametypes when there have been no players for 2 hours"
Now, there are basically no users in the classical sense. The modification in question kicks in automatically once it's been added to the server. Thinking ahead there would be a timer that would poll the number of players at a regular interval and then start a countdown once that number is zero. Then the timer would call a method that would trigger a change.
What Actors can you see in this description?
Timers are often modelled as actors in use case diagrams. I suggest you do so.