I've been thinking about what sort of shenanigans Grace and Rocky would get up to during the 4 years to Erid, and I like to imagine that at some point Grace is trying to come up with something new to fill the time and decides to ask Rocky if he can recreate a boardgame for them.
Rocky agrees, so Grace pulls up a photo of a basic snakes and ladders board and some dice for Rocky to replicate (with proper grooves so it's Eridian-accessible of course), and while it's fun for a little bit, Rocky eventually decides things need some livening up and modifies the board and rules to incorporate some features of a simple game from Eridian culture.
Turns out that the thought required for this interspecies boardgame hybridization is a fun way to pass the time, so they continue to go back and forth with games from each of their cultures, modifying and expanding the same board that they originally started with to conserve resources.
What ensues over the next couple years is some form of wild boardgame evolution resulting in the most convoluted and arbitrary set of rules that would be practically incomprehensible to anyone else on either planet, but they don't think too hard about this and decide one day on Erid that wait, we should try and teach Adrian!
Meanwhile Adrian is just left in abstract horror at the absolute disaster of a pass-time that these two nerds constructed like "this is what you guys had to do to stay sane??" And they're just like "yeah, we thought you'd like it!"
Intergalactic Calvinball!
