Cute little game. I really like the "ui" for choosing an upgrade.
I think that the frost overlay could have used a different sort of easing or something. I feel like it persisted way too long in a state where it was just vaguely muddying the graphics. It should do its thing obstructing your vision for however long it should, and then pretty quickly get out of the way.
Is this just pure ambient lighting? I think that a couple minor graphical tweaks might be really impactful: choosing clear color that fits the scene better, and adding a directional "moon light" so we get some shadows.
I found it sort of difficult to tell when a ghost was about to leave the range of the vacuum, and it looked a bit funny when they moved in and out of range. Maybe some sort of "grace timer" where they still get sucked for a small amount of time after moving out of range?
I also feel like you could have leaned a little harder into ghosts being a synonym for "entity." thing.
And I know this is not something everyone wants to do for a variety of reasons, but this is a game jam in a super code-centric free-and-open-source-forever engine where mostly programmers are participating. Let's see some source code!