How does you game fit the theme?
In 3 ways, first, you're literally not alone, you're surrounded by hamsters at most times; second, you're under the constant threat of spiders just out of sight(they tend to sneak up on you); and lastly, the game plays around with you then becoming alone temporarily by sacrificing your hamster friends to the machines to get turrets and torches.

Did you write all the code and made all the assets from scratch?
Yes, some of the .json saving code was made in an earlier jam, same with some other unused menu assets. But asides from that, it was all during the jam, including the art and the music.