The goal of Downstream Panic! is simple. A blob (or two) of water starts at the top of the screen, and when you press Start, it begins flowing downward into the environment. It’s your job to make sure that the fish contained in said water make it to the bottom of the stage in a safe manner, with sectioned-off areas of the lower water filled with vicious piranha. To clear the first level, all you need to do is use your trusty rockets to blow holes in two sections of the land, and your fish will gracefully flow into the ocean below.
After that, things start getting much more tricky. You’ll have to use a number of tools, like seeds that grow plants to stop the flow of water or fans that blow flowers to open bridges, but these are hand-selected and very limited in each level. Generally speaking, you start with the exact tools that you’ll need to complete the level and no more, so careful planning is necessary to complete the stages by saving the requisite number of fish.