Clever idea - I liked the unique mechanic of building a graph for the modules.
I didn't notice that I could chain more together, but that would have been interesting. It also seems like there's a limit to the number of connections between boxes - would be helpful to know how high that limit is when placing things.
Nit picking - the level up window isn't really necessary and gets irritating after a few levels.
Great work with lots of polish. Impressive!