Thank you so much for playing it and for the feedback! About the difficulty: all the people I gave that map to playtest found it too difficult, and I didn't really know how to make different difficulty presets for doom, so I left it at that. Next time, I'll make more difficult modes more difficult. And will try to be better overall. Thanks again for your feedback and overall support. It means a lot.
Viewing post in Level Design Jam 6 doom map comments
Interesting... well no offence to your testers but they must not be very experienced players. This is easier than most of the original Doom 2 maps! And the modern "meta" is far beyond that level. That's not to say that you can't make easy maps, and in fact I appreciate when people don't try to push the envelope all the time and just let you cruise for a minute (especially in a large set of maps).
The difficulty settings are found in the properties of Things, you should have some checkboxes that say "Easy" "Medium" "Hard" etc. When you select a difficulty level in the game, only Things that have that specific box checked will spawn. I'm too young and Hurt me plenty spawn "Easy" items. Hurt me plenty is "Medium" and then UV and Nightmare are "Hard". This applies to all things! Most commonly you would have more and tougher monsters as you go up. But you can also have different amounts of ammo, weapons... even different placements for keys, teleporter destinations, and obstacles if you want to get creative. But as a beginner mapper you would probably want to focus on the balance between monsters, health, and ammo.
Difficulty settings are not mandatory but they do make your maps more polished, and allow a wider range of players to hit that sweet spot of challenging but not impossible. There's a nice page with more detail about difficulty settings here:
https://doomwiki.org/wiki/Skill_level