Portal64 required you to have access to one file from portal 1, portal_pak_000.vpk. It’s trivial to get that file. Either via google, or purchasing Portal, extracting the file, then getting a refund.
Revolution requires a continuously working copy of Portal 2.
It’s significantly easier for the general population to play Portal64 without giving money to Valve than Revolution.
From what I read of the portal64 project it did require owning the original (or having a copy of it) because it patches the assets from the base game.
Portal64 required you to have access to one file from portal 1, portal_pak_000.vpk. It’s trivial to get that file. Either via google, or purchasing Portal, extracting the file, then getting a refund.
Revolution requires a continuously working copy of Portal 2.
It’s significantly easier for the general population to play Portal64 without giving money to Valve than Revolution.