Hi Mesaying, Thanks for your comment.
With the gameplay missing many parts I can see why it is hard to see the Theme.
The theme here is: A Malice has corrupted the people. You need to liberate the people's souls to then join their power (Fire Rate, Speed Boost, Damage Boost...) to defeat the source of the corruption. That should spawn after some waves. However, the spawn manager decides to die 20 minutes before the end and here is the result.
We should be able to make something better next GameJam we do. This is only the beginning! One done, thousand to go!