Your inventory is the the resources on the top of the screen.
No, it's not really what I think about an inventory ...
For example: If you walk outside and harvest wood you don't need to bring it into your house to build a pile of wood pides in your garden.
What i'd like to have is a more RPG - like inventory where the items I collect are stored and I can select which one I can store in the stores ;-)
I know about the technical issues, that would make changes in Source Code nessesary to use such an inventory. And of course I know what you used on top of screen. ;-)
A second improvement (maybe easier to do) would be to change messages like "You drank water" to status massages (like "Building can't be placed there" in original Glest for example) so you don't need to close two messageboxes after your character moved above a "water_fountian". ;-/
Anyway great scenario ... I like the RPG/RTS - mix ...