As a solution he should publish his game hash and make sure that everyone has access to it, if u download eternum then hash it, and the hash is different than the one provided by him means the download is corrupted.
My zip file for the 0.7.5 PC version has this SHA256 hash, downloaded in April this year: ea0fa8e630dc1f368d400cc969b4169316b81eba2dadb35659b18dcd3a8366c0
