This is a rough demonstration of an inventory-object puzzle.

Start

You are standing on a porch in front of a door. A grassy lawn is behind you.

Go inside.

Open the door.

The door is locked. You will need a key to open it.

Walk over to the lawn.

Go back to the Porch.

You are standing in a grassy lawn.

You see the glint of a key laying in the grass.

Congratulations! You’ve managed to get inside your own home.

Inventory:

Key?