for those still interested: 8, 2, 4, 6 are obviously numbers on the keypad on the keyboard. Like, literally, if you look at the right-hand-side of the full-sized keyboard, these four numbers have arrows printed on them: 8 is up, 2 is down, 4 is left and 6 is right.

Clever!
How did you think about it heheheheh!

dont think is an issue

But the tail is a 1 char string

It's done for many old games because this allows you to:

dx = (dir%3)-1
dy = (dir/3)-1
dir = (dx+1)+(dy+1)*3

In any case, it's arbitrarily defined anyway and it's perfectly fine to define them as sqrt(2), pi, e, Infinity too (even though that'd be bad and ridiculous).

Why Direction enum is 8, 2, 4, 6? Why not 0, 1, 2, 3?

In tests, there is no test for the length of the tail.("Fox", "xyzdsr") will pass, which should not be