One of the oldest splits within Indo-European was between the Centum and Satem languages; they differ in what they did to the "accented velar" phonemes (like *ḱ and *ǵ).
However, if I understand right, the Anatolian languages split off some time before the Centum-Satem division happened.
So, what happened to "accented velars" in Anatolian?