How would you define it if:

- the DRM/delivery software is open source

- the game payload is sent to you encrypted using the public key of a secure enclave on your computer

- while the game runs all its memory is symmetrically encrypted (by your own CPU) using a key private to that secure enclave. It is only decrypted in the CPU's cache lines, which are flushed when the core runs anything other than the game (even OS code)

- the secure enclave refuses to switch to the context in which the CPU is allowed to use the decryption key unless a convolution-only (not overwriteable with arbitrary values) register inside itself had the correct value

- the convolution-only register is written with the "wrong" value, by your own computer's firmware, if you use a bootloader that is not trusted by the DRM system to disallow faking the register (ie, you need secure boot and a trusted OS)

That doesn't seem to fit in any of your models. There's no online check, you can't send someone else the key because it's held in hostile-to-you hardware, you can't bypass the local-PC check because it's entirely opaque to you (even the contents of RAM are encrypted). You can crack into a CPU itself I guess?

I don't think the mechanism of the DRM being open source helps with the copying AT ALL in this design.

This design is, by the way, quite realistic: most modern CPUs support MK-TME (encrypted RAM mediated by a TPM) and all Windows 11 PCs have a TPM. Companies just haven't gotten there yet.

Thank goodness!