One idea would be for the game not to have a specific ending, since that way the game could be more interactive or more entertaining to see how much we could do in the game and see that we could interact with other characters and see how much we could discover.

There isn't a specific ending, there are multiple different endings that are triggered by the player choosing the (*insert name here* Ending) option from various characters. You can have the game go on for quite a while without ending it, so I don't know what you were asking for here.