I do not know if this counts but:

- change default port for sshd will take away 99.9% off all random attacks.

- many copy protections may count as this. Some of them uncrypt themself before running so that it is harder to disassemble the bin file on disc. Also some more creative protections have been around, https://www.makeuseof.com/tag/5-strange-video-game-copy-prot...