You have a garden with random plants scattered all around.
All you have is a single hose/sprinkler that you must use to spray water on all of them.
Upgrades obviously give you more water, a wider spray, faster movement and better aim of the hose, other flower types to help you, etcetera.
Related: doing the same thing but for washing dishes (with a huge garden hose or water gun or whatever)
2D or 3D (first-person?).
This would be a really cozy fun little game about tending to your plants, in a way that’s simple and upgradeable. At the same time, I don’t currently see how to get a full game out of this. What more can you do than the upgrades I already listed? What else?