Ironically, the last time I checked (which was some number of years ago), TextMate 2.0 did not support the TextMate 1.x theme format, not even via any sort of import or conversion mechanism. Which is odd, considering that it's become a de facto standard supported by other editors.
TextMate 1.x was the king of Mac text editors back in its day. Is anyone actually still using TextMate today?