Voyager was ArgoNet's Internet suite - to make getting online as easy as clicking a button, back in the days of dial-up modems when this was very much not the norm.
This is the default Voyager suite main window - the brief was basically to add as much colour and excitement as possible, while still sticking to the 16 colour desktop palette. Each icon had to be different enough to be immediately identifiable. Subtlety was not exactly high on the requirements list for this one. My original design for file transfer was a crane against a blue sky lifting a block, with a subtle cityscape behind it. Apparently this was "disappointing" and ended up as files flying between directories on an eye-searing orange lava "cyberspace" backdrop.
After a while I wrote a program called NewMail to intercept window manager calls from Voyager and make appropriate sounds, mainly to get that "You got mail!"-style announcement on a RISC OS machine. It was the kind of cool hack you could do with RISC OS. I was also doing icon packs, but you had to overwrite the original image files inside the Voyager suite.
Jason Tribbeck, the programmer, noticed this and by the time Voyager 2 came out it had official support for both sound and icon packs. The system was called VIXEN - Voyager Internet eXtension... ENgine?
One of the slight problems was that you could also package up programs and tools that could extend Voyager too, and if you didn't have icons for those, it just used whatever icon the author had provided, scaled to fit in.
This means that, as with the Alien-inspired pack (above), some of the icons didn't exactly fit the aesthetic. The chompy alien indicating new mail is kind of undermined by the light, flowery ICQ icon.
So, I just had to make packs with more icons in, to cover the main tools that people were adding. I couldn't get them all, but you were more likely to see a fully modified version of Voyager.
I was a big fan of the game Syndicate on PC, and when it got ported to RISC OS machines I tried my hand at writing an online guide (I didn't quite finish detailed outlines and strategies for every level, but at least I'd covered all of the start and end ones). Using the assets I'd grabbed or created for that, I created Voyager icon and sound packs, including painstakingly lettering the icons using individual cut-out letters.
And just to prove I could do subtle icons, here's an image pack just using black and white, and a whole lot of dithered pixels, very similar to what I [had been/would be] doing for mobile news web design: