Computational Substrates: How Well-formed, Self-replicating Programs Emerge from Simple Interaction - https://arxiv.org/abs/2406.19108
Brainfuck, Forth, Subleq, and most recently Z80 assembly programs with mutations, interactions, and self-modification. Z80 has an LDIR instruction that copies a block of data from one location in memory to another, which allows the "organisms" to reach/discover reproduction quicker and more reliably in repeated experiments. As soon as that happens, it inevitably takes over the "world".
Hm, sounds more like "Lord of the Flies" than Rings.