Why not the most primitive rockets of all? Fireworks Since they are a great foundation to learn from for young and old as well as being endlessly entertaining.
Since solid propellant already exists - maybe add a fuse instead of a nozzle with adjustable timer to have rockets detonate their dazzling payloads at various heights. Control over fireworks color & effects might be in a fireworks display options menu.
Flares can be a handy way to get a quick visual lay of the land when in a pitch dark area and can also be useful to signal positions. A flare like behaviour added to the fireworks display options could enable a flare to be launched as easily as any firework.