Point and click suggestion

Looking for a point and click puzzle game with certain criteria. I've never really played in the genre, so know very little.

I want for something the whole family can enjoy, which includes my 7 year old son.

Would want a game where:

• My 7 year old can contribute, but isn't boring for adults; i.e. somewhat difficult
• Art style that would appeal to a 7 year old boy
• On PC
• Mouse only
• No addictive, reflex gameplay; should focus on thinking
• No intense timed sections (want him to have time to think)
• Age appropriate content