Hey anchorlight :) Great to hear. And yeah the first level has some issues with lighting.
Every island (except 1, which is below the death barrier) is accessible! It's all about how many rockets you can click out, so APM matters. Launching yourself off of a wall rather than a flat surface also lets you gain even more speed. The final island in level 3 is tough to really get onto, since you have to jump from a super tiny (and flat) island. Usually takes me a few tries to get it. So yeah some signposting there would've been a great idea.
We're mostly new at unreal (and gamejams) in general, so you could definitely learn how to do something like this pretty quick. It was pretty much an hour or two of Youtube tutorials :D I can send ya a few links to the ones we used if you'd like?