Let’s address the elephant in the locomotive shed immediately:
expansion on the official website or GOG allows you to redeem a free Steam key for the expansion. Factorio Forums Avoid Scam "Free Key" Sites factorio free steam key
Users searching for a “Factorio free Steam key” will only find scams, malware, or disappointment. The developer’s anti-sale policy is intentional, designed to respect early buyers and avoid pressure tactics. The safest and only reliable ways to play Factorio are purchasing directly from Steam, the Humble Store (official widget), or the developer’s website, or trying the free demo. No paper, bot, or website can generate a valid free key. Let’s address the elephant in the locomotive shed