You can legally download the of Doom (1993) for free . This version includes the entire first episode, "Knee-Deep in the Dead," but requires a purchase to unlock the full game. 🚀 How to Get the Free Shareware Version
Source ports are modern engines that use the original game data to run Doom with better resolution, controls, and compatibility. Doom 1993 Free Download
The shareware version consists of the first 9 levels of the game. You can legally download the of Doom (1993) for free