This is a very promising game! The way that you have to learn how your input works gives this game the potential to explore many unique ideas. I would love to see runes that mess with the properties of the line, such as how it interacts with shapes on the board. I also hope you explore rune count more, like limiting the amount of a certain rune, as even this demo has some clever tricks for reducing your rune count. After optimizing several times, I got down to 81 runes used, which I conjecture to be the minimum (pun intended).
Also, when accessing the Settings from the main menu, the header says "SSettings," which I would assume is a typo.