The Steam distribution of First Snow ships without 18+ content due to platform content policies. The above patch will re-add this content to the game. This patch is provided without warranty; you have to be of legal age in your jurisdiction to use it.

To install it, go to your Steam library and right-click the First Snow entry. Navigate to Manage and then click Browse local files. Drop the file linked above, dlc_h.rpa, into the subdirectory called game. Restart First Snow, and you will notice a + symbol will have appeared next to the logo. You are now good to go!