While the game has a free demo available on some platforms, "ZERO Sievert" is a paid title. You can find the official version on Steam or GOG. Be careful with sites offering "free downloads" of the full game, as these often contain malware or pirated files that can harm your PC.
The narrative isn't told through cutscenes, but through the tension of your daily life: ZERO Sievert PC Game Free Download
Back at the bunker, you use your loot to upgrade your base, mod your weapons, and take on tasks from various NPCs that slowly reveal the lore of the collapse. Atmospheric Storytelling While the game has a free demo available