The patch does not change the main romantic storyline. The game remains a “true route” romance with a linear plot; the adult scenes are integrated as extensions of the relationship development.
Before the official DLC was released in late 2018, users relied on patches from external sites like Denpasoft or Neko Works' Booth. Nekopara Vol. 1 Steam 18 Patch
The is an official, developer-sanctioned downloadable file (typically 300-500 MB) that, when applied to your legitimate Steam copy, unlocks: The patch does not change the main romantic storyline