Here is a concise summary of the text:
**Title:** Completing DOOM II within DOOM Eternal's Easter Egg
**Summary:**
* The author discovered an Easter egg in DOOM Eternal allowing them to play the original DOOM II within the game.
* Intrigued, they attempted to complete DOOM II in one sitting (due to save file issues) and recorded their experience.
* The playthrough was challenging due to lack of maps, ammo scarcity, and confusing level design.
* Despite obstacles, the author enjoyed the game's fresh gameplay, unique OST, and discovered hidden secrets, including a Wolfenstein secret level.
* They ultimately completed the game, defeating the Icon of Sin, and reflected on the experience, encouraging viewers to try classic games like DOOM.
Here are the key facts extracted from the text, excluding opinions, with each fact numbered and written as a short sentence:
1. **DOOM Eternal** contains an Easter egg allowing players to play the first and second **DOOM** games.
2. The classic **DOOM** games within **DOOM Eternal** can only be saved while the player's character, Doom Slayer, is present in the Fortress of Doom.
3. Exiting the game or playing any stage in **DOOM Eternal** causes save files from the classic **DOOM** games to be wiped.
4. The map feature does not work in the classic **DOOM** games when played through **DOOM Eternal**.
5. Completing the classic **DOOM** games within **DOOM Eternal** must be done in one sitting due to save file limitations.
6. **DOOM II** in **DOOM Eternal** includes a secret level, which is actually a level from **Wolfenstein**.
7. The **Wolfenstein** level in **DOOM II (DOOM Eternal)** had its Nazi symbols censored.
8. Commander Keen characters must be killed to progress in the **Wolfenstein** secret level.
9. A bug in this version of **DOOM** prevents players from seeing the number of found secrets.
10. The Icon of Sin boss in **DOOM** is essentially a texture on a wall with a hitbox modeled after John Romero's head.
11. The Icon of Sin summons mobs in large numbers and requires players to hit a small, specific target to defeat it.
12. There is no traditional aiming mechanism in the classic **DOOM** games; height plays a significant role in combat.
13. Completing **DOOM** within **DOOM Eternal** yields no achievement or special recognition.