Here are some free ideas you can use if you are stuck on the theme, The More You Have, the Worse It Is..

• Remake of Atari classic Plaque Attack; the more gum disease you have..
• Docker; you work at a dock where ships come in over-burdened. You have a (reverse) time limit to remove their cargo before they sink. Perhaps additional ships as levels increase.
• You work in a postal sorting office; post comes through a chute, you have to sort the post into the correct outbound slots. Points for correct, time deductions for incorrect. Get it all done before the time runs out.