HellSound Dreams
Size : 829MB
Horror type map. Recommended for fans of "Cry of Fear" and "Afraid of Monsters."
DoomED
Size : 91.60MB
I only put this here because I remember playing this a long time ago and it recently appeared again on PlanetPhillip. It's a non-action map that starts out in a London train station during WW2. There's walking, exploring, and puzzles.
HuntDownTheFreeman - 24 Hour Remake
Size : 13.80MB
It's a parody mod and only 13mb, but it's just for a laugh. The author that made this loved "Hunt Down The Freeman" so much he remade the campaign in less than 24 hours. From the description: "To sum up, play this if you want a laugh and a wry smile, but don’t go looking for fun gameplay or cool situations."
The Transformation
Size : 10.3MB
Low file size but PlanetPhillip got 25 minutes of playtime out of it and I like "Rats"-style shrinking maps.
L4D2 - Crash Bandicoot Return of DR Cortex
Size : 160MB
This looks so goofy but interesting. I never played the Crash games, so I can only comment that if you like weird, funny, low poly maps that gets straight to the point then play this. And maybe if you're feeling nostalgic. Video playthrough here.