How to override package version

You need to explicitly pass in the params to the overlay. I think this should work in houdini.nix:

self: super:

{
  houdini = super.houdini.overrideAttrs (old: rec {
    name = "houdini-runtime-${version}";
    version = "17.5.229";
    src = super.requireFile {
      name = "houdini-${version}-linux_x86_64_gcc6.3.tar.gz";
      sha256 = "b20e0f35c51479fe3f89489ad64122b96f9d14eab26b54dbc062fdbb1681f5e0";
    };
  });
}