There are a lot of strange things that can be pointed out about the Teeworlds User Interface. It’s kind of unique – never seen anything like this in any other game, at least.
At first, how the text areas are handled. Usually, it’s a whole, an object with properties like size of the box, text, etc… In Teeworlds, it’s more about drawing a light grey quad, and then printing a label with what you wrote. It becomes pretty confusing when you are reaching the end of the text area, the label keeps being rendered, without any regards to the overlapping problems. This also makes impossible to use this kind of form:
Secondly… everything is just so big!
I can understand this fits the KISS style, everything big, simple, but the UI is very quickly becoming fluffy when you try to add something more consequent than one or two checkboxes. It’s really a pain sometimes to insert features just because of that UI (e.g. the ingame server browser).
Another surprisingly noticeable point: the silence! The very most of the other games play little sounds when you click a button, close a window or open it, pop up a little warning, or even write some text; and Teeworlds does none of that.
That’s really some little points I’m missing from other games with the Teeworlds UI, but it happens some players enjoy them (such as severely visually impaired people, I guess).