Hello!
What do you mean by "serious"? (because that's not the word i would have used for Liar Game or Ouroboros). Well, at least i would recommend some who might remind you of what you're currently watching or have liked: Kurosagi (which is on your Plan to watch list), Kazoku Game, Maou, Kazokugari, Bloody Monday (2 seasons), Keizoku 2 : SPEC, Ando Lloyd (on your PTW if i remember well). Maybe Hanzawa Naoki, not totally the same, but one of the best.
Those are dramas that I really enjoyed, as well as the two you mentionned.
Hope it could help, and have fun watching some of those dramas.