I'm not sure where I got the idea from exactly, but I decided I'd have a go at recreating the original Doom E1M1 in the style of Doom 2 MAP01. In that I think I've succeeded, although there is a little bit more detail in this than the original levels of either Doom 1 or 2, and I couldn't resist using a couple of new flats in places.
After I'd finished the layout, I realise I might as well have ago at improving the gameplay a bit. After all, I know it's the easiest setting, but a grand total of FOUR enemies on I'm Too Young To Die? Now there's 19 on this setting, 32 on medium and 47 on hard.
DM has also been given a fair bit of consideration, and you should find it plays considerably differently than Doom E1M1. Perhaps the most important difference is that the central outdoor area now serves as a crossroads rather than a dead end.
BTW, listen closely and even the E1M1 music has been slightly changed to more closely match the music from MAP01. Ditto for the sky.
ID Software for E1M1 and MAP01.
The author of neutered.wad for the 'fixed' SUPPORT2 and DOORSTOP textures.
All new level from scratch (though heavily inspired by E1M1 & MAP01)