I'm very glad that you enjoyed and even more that you beat it, as we were worried about balancing.
About the shells we may be revisiting colours, but also adjusting sprites as the hexes ended up smaller than anticipated. Actually downloadable version with full resolution should already be a better experience.
I haven't thought about danger types giving clues about surroundings kind of design, but I like it! We are actually thinking about what to add, so all ideas are much appreciated!