Scientist2
Sci2.wad

Author: Scientist
Not port specific, Doom2 Map1-20 SP.
Very good arcitecture and playability (4-4), a bit dark.
Some archviles

Strain (32 level megawad)
Strain10.wad

Author: The Alpha Dog Alliance
Not port specific, Doom2 megawad.
Map01-32
Good looking.
Well playable.
Darkish.
Total Conversion.