You can buy it directly from the creator at undertale.com . 💻 System Requirements You don't need a gaming rig; a basic laptop will work fine. OS: Windows XP, Vista, 7, 8, or 10/11. Memory: 2 GB RAM. Storage: Only 200 MB of free space. Graphics: 128 MB or better. 🛠️ Step-by-Step Installation (Steam) Create an account: Sign up at Steam . Install Steam: Download the Steam client to your PC.
Go to your Library , click on Undertale, and hit the blue Install button. Undertale Download PC Game
Often includes a Steam key and a direct download. Check the Humble Bundle Store . You can buy it directly from the creator at undertale
Search for "Undertale," add it to your cart, and checkout. Memory: 2 GB RAM
The most popular choice. It handles installation, updates, and cloud saves automatically. You can find it on the Steam Store .