1RB2LA2LC---_1LA2RB2RD---_3RB1LC1RD0LA_3LA1RD1LC0RB

1RB2LA2LC---_1LA2RB2RD---_3RB1LC1RD0LA_3LA1RD1LC0RB (bbch) is a non-halting TT(2,4) TM that is "pretending to be" a probviously halting Cryptid.

Rules by Shawn Ligocki:

C(a, b, c) = 0^inf 3 2^a <C 1^b 2^c 3 0^inf = 0^inf 3 2^c 1^b D> 2^a 3 0^inf

C(a+1, b, c) -> C(c, b+1, a)
C(0, b, c+3) -> C(c, 0, b+6)
C(0, b, 2) -> Halt(b+7)
C(0, b, 1) -> C(b+5, 0, 2)
C(0, b, 0) -> C(b+2, 0, 5)

Start: C(1, 0, 2)  @13

Insight by dyuan: if you take all parameters mod 3, the config is always C(r+2, r+1, r) which is invariant under rules:

C(a+1, b, c) -> C(c, b+1, a)
C(0, b, c+3) -> C(c, 0, b+6)
C(0, b, 1) -> C(b+5, 0, 2)

and thus it can never hit the other 2 rules.

Discussion: https://discord.com/channels/960643023006490684/1395113664905744585