I think what made me quite confused at the start is mis-reading the instructions that every district could have no more than four houses; I thought I had to split the land into equal areas. Once I understood that, the solution felt much easier.

> If two parties tie in a district, nobody wins it.

This isn't realistic as ties don't happen in practice in elections, and some party will end up representing it. But the spirit of the gerrymandering concept is conveyed well enough.