This is an initial /k/ and initial /g/ articulation game I played with my preschool client.
Each session I printed a different picture (e.g., Winnie the pooh, Angelina ballerina, Tinkerbelle) and placed it behind the doors. My client would go through the stack of keys, producing the initial /k/ or /g/ target words on the back. When she found the magic key we would pretend to unlock the doors and find the picture behind them, which she could take home.
Instructions on how to assemble the door and pictures are included in the download.