I'm a special box

Boxes can be boring and uninteresing, but in this word guessing game you'll meet six different special boxes. Can you figure out what makes them so special?

Made in 3h 30m (excluding planning) for Trijam #325. I thought I was gonna make it under the 3 hour mark, but I desperately needed som playtesting from others which took 20 minutes, and I needed 10 extra minutes to fix some issues.

Use the hint button (lights up after 20 seconds) if you feel stuck. It'll give you the first letter.

The music was made by me earlier this week, and it ended up fitting the vibe perfectly.

There is a bug with how it's always the leftmost letter of a type that gets disabled when you click it. This was due to how I implemented it early and when I found out about the issue it would've sadly taken to long to fix (I'd have to redo most of the system).