Here are the details regarding the game and the download status:
For English-speaking fans, the only way to experience the full story is via the fan translation group Committee of Zero (known for their definitive patch of Steins;Gate 0 and Chaos;Child). steins gate variant space octet download
They have released an English patch for the Steins;Gate: Variant Space Octet PC release. However, they do not provide the game files themselves. To use their patch, you must legally own the Japanese version of the game. Here are the details regarding the game and
Unlike the point-and-click menu system of the original, Variant Space Octet is a retro-style command-line novel. The entire game is presented through an 8-bit computer terminal aesthetic. You do not click on Rintaro Okabe; you type commands into a DOS-like interface to interact with the world. Google Play Store (Android): Search for Steins;Gate: Variant
The game is infamous for its difficulty. To progress, you must type specific Japanese (or English, in the fan translation) commands such as look at phone, talk to Kurisu, or call Suzuha. If you type the wrong command, the game kills you. Immediately.