So let's say I wanted to have the protagonist of my game pick up a Key and a Stick. My original idea was to just make duplicates of all the rooms (except with them now acknowledging you had a Key and/or Stick when you were to enter, say, a room with a Locked Door in it), but after some thinking I've realized that I'd need to make well over 200 copies of the entire map, since some parts of the game would need you to be holding more than one item at a time. This would take a loooong time, and I'm really not good at coding at all which makes matters worse. So I was hoping someone could somehow explain to me how to make a proper inventory system, that would make certain rooms acknowledge items or prompt them to be used, as well as removing/keeping them after use. Thanks if you can.

is this for Text Adventure or Game Book versions ???
is this using the offline/desktop or the online/web versions ???

(the Text Adventure already has an qausi/partial inventory system, though you can certainly make your own to be more robust/better for your design needs, but depending on what you need for your design, it can be very, complex/difficult and/or a lot of work, to do/code it in)

before we can begin to help, we need as much details about what you need from it (and as well as which quest you're using: Text Adventure or Game Book, as the game book is much more limited, which means it uses a different design than the many designs you can do with the text adventure