Use Case Diagram - Create Character and Create Another Character
I have three use cases:
1) Create Character
2) Create Another Character
3) Delete Character
Is Create Another Character the same use case as Create Another Character since they have the same functionalities? If they are separate use cases, does Create Another Character extend Create Character?
Another problem is that Delete Character is not possible without first creating a character. If Create Another Character is a separate use case from Create Character, does Delete Character extend Create Character or Create Another Character? Or does Delete Character extend both of them?
Create Character will be just one use case. You don't need to repeat use case for each object to create. Even if you might have dependency to already created objects (e.g. You have a limited unique list of available characters so each new has to be different than already existing) you'll handle this impact on describing details of a use case (in different diagrams, like activity diagram showing the steps user has to convey to complete the use case or in plain text).
Delete Character will be a separate use case. However that's with assumption that deletion of character may be separated in time and isn't always conveyed in the same session as creating the character and using them (e.g. Running a quick game)
You might have a situation where you can create multiple characters in one go. Then instead of Create Character you'll have Create Characters. Or you may have Initiate Game that covers everything that needs to be performed in order to be ready to start to game. Or even, as already mentioned you may have a single use case Play Game that covers the whole setup, playing and deletion of the game.
In general your use case should be what you do in one session without breaks and pauses. They are also abstract in a way that they can be run multiple times by the same person (user) our by various persons in the same role.
Do not use use cases to decompose the order of running them. It's not the goal of use case diagram. You'll be handling that elsewhere.
I recommend reading some books about either business analysis in general or specifically writing use cases.
Create Another Character will only be a new use case if there is something materially (business wise) different about it.
"Create Character" and "Create Another Character" is the same use case,Because the features of both are made up a same form . Another problem,To clarify this problem we can use "View Character" a new use case which includes a list of registered characters.In this case you can be "Delete Character" from this list.You will also be able to "Edit Character" in the list.
///see the diagram