Original DOOM is fun. I just played it for the Nth time through a few weeks ago. Was in the mood for a round of DOOM for some reason so did a complete play through (Three episodes) on Ultra Violence, all secret levels, no cheats of course. Cannot beat Nightmare without editing though. First played it back when I was a teenager in the 90s.
I still have my original copy of it, version 1.2 for DOS. I copied it onto CD though as the floppies are unusable now. That old version only has three episodes and is missing a few map features present on later versions such as the secret switch right at the beginning of E 1 M 1
: Hangar. On an interesting note E 1 M 4
: Command Control still has the swastika shaped room, they bowdlerised it in version 1.4.
Unfortunately, on that early version very few mods work, most need version 1.666.
Mary had a little lamb... but I ate it.