While the first episode of the original 1993 game was famously released as free shareware, the complete expanded edition known as The Ultimate Doom is a commercial product that must be purchased.
If you tell me what operating system you are using, I can guide you on how to get the classic shareware version running safely. Ultimate Doom Free Download
Be highly cautious of any websites offering "free downloads" of the full game, as these files are unauthorized and frequently bundle harmful malware. 🕹️ How to Play Legally and Safely While the first episode of the original 1993
