Death Billiards is GREAT stuff. Deserves a 4/5 on douban hands down. I think that if this OVA was longer (like a 1 hour 30 minutes full-length movie), it could have potentially been ranked in the masterpiece category, for only some achievable conditions were met. Yes, if the themes of the show that are already here were more developed, if the animation & visuals were just as good, if the cool factor was continuously played & timely placed as a surprising variation of the show's flow, if the psychological & very human part was even more emphasized and developed... etc, then it would have deserved this status.
But since Death Billiards is only a 25-minutes anime (just as long as an average series episode), it's hard to see if the show deserves so much praise: it's much easier to do a goddamn job when there is not enough time for chara-development (and therefore no possible evaluation on…