> mCaptcha uses a Proof-of-Work (PoW) based algorithm to offer Denial-of-Service protection

if you want denial-of-service protection, wouldnt it be better to use a delay-based algorithm, instead of a proof-of-work one?

Proof-of-work is not environmentally friendly, wastes your legitimate users resources, and doesnt stop all DOS types

Just force a delay in time to requests to your site and allow only as many as you can process