What options do gamers have?

1. No games

2. Inscrutable rootkit

3. Piracy

4. Attestation, i.e. partial Tivoization

Of these, #4 seems least awful and maximally user freedom preserving. Unlike regular Tivoization, also, we're not talking about locking down the whole machine. No need. You basically just need to attest the kernel and some binary signing infrastructure. You can run custom builds of whatever else you want otherwise.

I mean, or you can run a trusted VM, as some others have suggested. Is that really any worse?

Another option is to use servers that do not require the anti-cheating, or to play vs others who do not require the anti-cheating, or to use a local network with dedicated computers for this purpose, or games that do not have these features, or only play vs other trusted players within a group that you trust.