You can argue that this show isn't that "obscure" since it literally finished airing this week and had its fair share of viewers (one of ANN's reports on viewership ratings in Japan had this show with a rating of 3.4, which for a late-night anime is really damn good, I believe). Still, I reviewed Season 1, so I should definitely do this show as well.
This past February I reviewed Gyakkou Burai Kaiji: Ultimate Survivor and downright gave it absolute praise. It's interesting characters, crazy gambling games, and overall tense-as-all-hell style was just absorbing and easily made its way as one of my absolute favorite anime of all time. At the end of the last episode came a short segment where creator Nobuyuki Fukumoto, voice actor Masato Hagiwara, and the segment host herself revealed that a second season of Kaiji would be coming out, with Fukumoto promising that the wait would be about 1-2 years. Well, it took 3 years but Kaiji finally got its second season, complete with advertisements that teased Kimi no Todoke (the show that Kaiji took the time slot of, and called "KimiTodo" for short) fans and called itself "Yaku/Anti-Moe Anime". Now, 26 episodes later, Gyakkou Burai Kaiji: Hakairoku-hen/The Suffering Pariah Kaiji: Destruction Record Chapter has ended and not only has it been as good as the first season, but it's actually surpassed it!
[3/2016 ADDENDUM: Since this review, this season has now been given the official English title of Kaiji: Against All Odds]
[NOTE: This review will contain spoilers regarding the end of Kaiji Season 1, so read at your own risk... Though why you still haven't watched Kaiji yet, if you haven't, astounds me.]