Best games under a $1

Obligatory Bad Rats Show

Stuff I've played myself and definitely recommend:
Costume Quest
Fox & flock
Poker Night at the Inventory

Stuff I haven't played(yet) but heard mostly positive things about:
Diehard Dungeon
bit Dungeon II
Cubicle Quest
Psychonauts
Wanda - a beautiful apocalypse
Stacking

Stuff I haven't played and haven't heard anything about but look promising imho:
Paper Train Traffic
Almightree: The Last Dreamer
Tavernier
Haunt the House: Terrortown
Calico & Co.

Shutter
Millennium
Kairo
Before the Echo
An Assassin in Orlandes
Fox&Flock

FULL DISCLOSURE: I haven't actually played any of these, but they're on my wishlist

How about Paper Sorcerer? Anyone played it?

These were on my wishlist what are under 1€, i don't know if all of them are good:

Geometry Dash
Need For Drink
Final Take
Almightree:The Last Dreamer
Tribal Pass
Watch This!
Investigator
Lumber Island-The Special Place
Dungeon Nightmares II
Dispatcher
Urban Trial Freestyle

Nation Red - Good reviews and some people I trust recommended this one as well.

Ichi! http://store.steampowered.com/app/300300/Ichi/

Serious Sam 2 is 0.99. Its kinda the black sheep of the series but its still fun!

Are free games allowed? Sang Froid Tales of Werewolves costs less than a penny, but it's one of those games that is so good you'd wonder why it's free.

Portal

Darkstone, good Hack'n slash was on Playstation too !

http://store.steampowered.com/app/320320/Darkstone/?l=french

http://store.steampowered.com/search/?snr=1_7_7_230_12&term=velvet+assassin

I always recommend this game. It is way underrated for the price of 0.54 (canadian dollar). For those who can't get it to work can follow the instructions under the discussion page. This is a stealth game with some action incorporated. The atmosphere is awesome. The scenary might be a bit repetitive in an orange glow. The last 2 missions are hard as fuck. Other than those problems I would rate this game easily 8/10.

Deep dungeons of doom. A mobile transport. Simple but addicting game.

I played and beat both games.

Shadow Ninja: Apocalypse Only €0,24 for the Ninja Bundle
Goat Simulator DLC's €0,99 Each DLC

Nice suggestions here! I need Calico & Co. for obvious reasons (kittens!!!) so it might be one of my purchases this sale.

Fortix. It's dirt cheap and actually pretty fun. There used to be a bunch of Fortix giveaways when it was the cheapest game on stream. Now several games costs the same and even less. Fortix 2 costs under one dollar during sales but normally a bit more.

Dawn's Light
Penny Arcade's On the Rain-Slick Precipice of Darkness 3+4
Cthulhu Saves the World
Half Life 1/2
Portal
Postal 2
Deponia
Sword of the Stars: The Pit

• Ephemerid ($0,49)
  http://store.steampowered.com/app/335920/Ephemerid_A_Musical_Adventure/

• Advent Rising ($0,99)
  http://store.steampowered.com/app/3800/Advent_Rising/

• Postal 2 ($0.99)
  http://store.steampowered.com/app/223470/POSTAL_2/¨

Handsome Mr. Frog (0.49$/€)

Payroll

Euro Truck Simulator

Yes, do under $5 too :)
You can even use the same thread, just put titles like under $1 games, then under then put under 5, and so on... so it's one long list split in 3.

Actual Sunlight - haven't played this yet, but it looks promising. Currently 90% offf (€0,49)