Improve Stories to Make Features Testable
The stories as you've posted them violate the INVEST criteria. In particular, your stories lack testability. If you had testable stories you'd have self-evident, testable acceptance criteria for each story. Consider the following example:
As a level 4 character
I need to be able to do 48 hit points of damage per second
so that I can successfully fight the 4th level boss.
You now have a meaningful feature to work towards. This feature suggests two obvious tests, and a lot of inferable tests. For example:
- You can test the level 4 character stats against a defined target (whatever is required to deliver 48 damage per second) to see if your character-progression curve is balanced.
- You can test whether the level 4 character has been able to amass enough money to buy weapons that can do at least 48 hit points of damage per second.
- You can test whether the money/cost system for weapons is sufficiently balanced.
- You can test whether the 4th level boss is statistically beatable by a 4th level character outfitted with appropriate weapons.
Compare this to your story:
As a player,
I want to buy weapons from merchants,
so that I can progress further[.]
Vague stories with vague goals and unmeasurable success criteria lead to all sorts of problems, including simple definitional problems like "What does 'progress further' actually mean within the project?" Most of these problems go away with properly-written stories because you then have measurable goals, but you will still have plenty of work to do in properly defining the implementation details.