on first 3 maps its quite possible to achieve 2147+ rounds and der riese i dunno >.> depends how good u are . but this can only be done in solo (unless u wanna play for a month straight with more players lol..)
got to round 17 in shi no numa by myself. used vandzway, but didnt get so lucky in guns. had thompson and magnum, went to mysterybox and it was a dog round, so i got killed by a dog.
43 solo and 24 with 4 or 3 people.
its kinda hard, not only due to more zombies, but the others always want to camp at the mystery box, even if they have an MG or Browning. i just buy a thompson and i dont think i throw that away.