Fully Descending
Downhill all the way, no brakes.
From the second digit on, each digit is exactly one less than the previous — the whole string steps down in lockstep, like 321, 9876 or 654321. RNGdle requires at least 3 digits.
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Fully descending is the mirror image of fully ascending, but with 4 extra seats: 26 in range versus 22. The difference is entirely about zero — it can stand at the tail (210, 3210, 43210, 543210) yet never at the head. The downhill road is slightly wider than the uphill one.
Counting by length: eight 3-digit (210 through 987), seven 4-digit, six 5-digit and five 6-digit. The theoretical limit is the ten-digit 9876543210, but with the range ending at 1,000,000, the longest landing is the six-digit 987654.
As with ascending runs, steps of exactly 1 flip parity automatically, so every fully descending number also hits Alternating Parity. The Straight, however, only honors the upward direction — 654321 falls beautifully but earns no straight.