[Cubix], 11 bytes, byte sum 954 (ASCII)

Code:

vOw~N(!@O^|

Output:

998877665544332211

Verified here!

[Try it online!][TIO-j5k5575k]

Cubified:

    v O
    w ~
N ( ! @ O ^ | .
. . . . . . . .
    . .
    . .

Watch it run [Cubix]: https://github.com/ETHproductions/cubix [TIO-j5k5575k]: https://tio.run/##Sy5Nyqz4/7/Mv7zOT0PRwT@u5v9/AA "Cubix – Try It Online"

[Cubix], 11 bytes, byte sum 954 (ASCII)

Code:

vOw~N(!@O^|

Output:

998877665544332211

Verified here!

[Try it online!][TIO-j5k5575k]

Cubified:

    v O
    w ~
N ( ! @ O ^ | .
. . . . . . . .
    . .
    . .

• N initializes the stack with 10
• (! decrement and test for truthy
• @ on zero halt
• O^O output current number redirect to top face and output again
• vw redirect back to the ( decrement to begin the loop again

Watch it run [Cubix]: https://github.com/ETHproductions/cubix [TIO-j5k5575k]: https://tio.run/##Sy5Nyqz4/7/Mv7zOT0PRwT@u5v9/AA "Cubix – Try It Online"