First I added it as a non-steam game, forced compatibility in the options, set it use a shared compactdata file via the Steam launch options (STEAM_COMPAT_DATA_PATH="/home/.local/share/steam/steamapps/compatdata/shared %command%), then I downloaded C++, etc. the game needs to run, added them as non-steam games as well, forced compatibility, and set them all to share the same compactdata file as VotV.
Can get 60 FPS with shadows turned off and 30 with them on.