I'm gonna be the voice of boring caution here and say you should really just buy it. Not trying to be a corporate shill, but the legal route is the safest, full stop. 'Steins;Gate' is on Steam, the JAST store, and sometimes GOG, and it goes on sale pretty regularly. I got my copy for like fifteen bucks during a Steam winter sale.
Downloading visual novels from random corners of the internet is asking for trouble—malware, broken files, weird patches that mess with the script. The official releases have all the patches and sometimes bonus content baked in. Plus, supporting the creators means we might actually get more of these localized, you know? The peace of mind knowing the game will just work is worth the price of a couple sandwiches.