I've put a lot of time into this and unlocked almost every achievement, but I still can't guarantee your answer. Steam's offline mode usually works for games without third-party DRM, but some single-player titles check in on launch anyway. Look at the store page's right sidebar for a DRM section; if it only lists Steamworks, you can set Steam to offline and test it yourself. Updates are another thing though, you need online to download any patch, no way around that. I won't promise you anything, because publishers are scumbags, but that's how Steam handles most of my library.

check drm section on store page

buy it and if it snitches just refund before 2 hours lmao