How can I go about buying the video game Amnesia: The Dark Descent?

I live in America and i've been seeing reviews and trailers for this game and I think it looks terrifying. I would LOVE to play it. But I can't find anywhere online that has it. I've checked amazon, ebgames, best buy, etc. Does anybody know how I can go about buying this game in America?How can I go about buying the video game Amnesia: The Dark Descent?
they have a website.

www.amnesiagame.com

choose the buy now option and pick the download that you want.

Steam offers the game as well.How can I go about buying the video game Amnesia: The Dark Descent?
http://store.steampowered.com/



Amnesia is 33% off This Halloween ONLY

Original Price $19.99

Halloween Sale: $13.39



Reasons to register and download steam program:



1) "INSTANT ACCESS TO YOUR FAVORITE GAMES"

"Over 1,100 games are available to purchase, download, and play from any computer."

(Provided you have steam installed ONLY 1.5MB)



2) GAME SAVE BACKUPS / CD KEYS

- Some games have an auto backup called "steam cloud" basically saves your game files in their data base. No more worries of ever losing save files that you put all your hard work into.

- You NEVER have to worry about losing a CD Key because when you buy games it saves to your account where you always have access to.



3) GAMING COMMUNITY

- Has a simple interface for friends integrated in the software so you can chat with friends while playing any full-screen game, and therefore a great community for gaming.. think of it like Xbox Live on PC but without a subscription..



5) The Steam Valve Corporation CONSTANTLY has great to amazing deals from 50% - 85% off games during Holidays or Special Events.



6) "AUTOMATIC GAME UPDATES"



VERDICT

Anyone who plays PC games should use steam.How can I go about buying the video game Amnesia: The Dark Descent?
http://www.amnesiagame.com/#buy

Click one of the online providers to purchase it.