Ndeql

Ndeql is a non-deterministic variation on Sceql thought of by User:Koen as a continuation of the Knight Shuffling Tower idea. Just like Sceql, it provides a single queue of bytes as the only form of memory available to programs. However, that queue has a particularity: it goes with n variables, holding one byte each, which all act as its front element. For every "pop" operation, one of the n variables is selected: it is used as the front value, then replaced with the next value in the queue.

Just like Sceql, the queue in Ndeql can only grow and never shrink: data can never be removed from it once enqueued into it. Initially the queue is empty, and there are 3 variables, each holding a 0.

Computational class
Sceql was Turing-complete. Ndeql's non-determinism creates fundamental problems: There is therefore no way to guarantee that a program will complete an arbitrary large computation.
 * Variables start out as zero.
 * When a variable is zero, there is a nonzero probability that it will not be changed, but will be selected for all  commands, leading the program to halt without further iteration.

External resources

 * Interpreter in C.