Inundo is my first ever venture into table-top RPG system creation. I made it for the Rzut Na Inicjatywe (Roll For Initiative) contest, where the main constraint was that the final work should be under 50 thousand characters, and the winner's system would be printed.
My main inspiration while working on Inundo was the 1995 Kevin Costner's Waterworld - I realized that there is not a post-apocalyptic system where the 'apocalypse' was a giant flood. I decided to put my creation not on Earth, but on another planet that was 'colonized' by humans, but where two more races already lived - bird-people Aerons and the fish-like Aquarens.
Another inspiration was in the naming convention - I wanted it to feel somehow outlandish while still having meaning, which is why I used Esperanto to name a lot of things, places, and even the system itself (Inundo is Esperanto for flood).
I originaly created a mechanic system for the book, but after the contest I decided that it was a bad idea, and went with already established FATE System to carry the mechanics.