This is where measured boot and remote attestation come in. You can run whatever software you like; but will only be able to attest to running what you're at ac

This is where measured boot and remote attestation come in. You can run whatever software you like; but will only be able to attest to running what you're at actually running (baring an attack on the TPM or some other trusted component earlier in the chain). The remote game server would then need to decide if it wants to let you connect given your inability to attest to running a trusted configuration. I've seen this setup work in very controlled conditions. But given how diverse the ecosystem is, someone is going to put out a buggy system, and too many legitimate users will buy it for most games to be willing to blacklist it.