Just found your question whilst trying to solve another problem I'm having, you will find that currently Google isn't able to perform a temporary download so therefore you have to download instead.
To make certain file types OPEN on your computer, instead of Chrome Downloading...
You have to download the file type once, then right after that download, look at the status bar at the bottom of the browser. Click the arrow next to that file and choose "always open files of this type". DONE.
Now the file type will always OPEN using your default program.
To reset this feature, go to Settings / Advance Settings and under the "Download.." section, there's a button to reset 'all' Auto Downloads
Google, as of now, cannot open w/out saving. As a workaround, I use IE Tab from the Chrome Store. It is an extension that runs IE - which does allow opening w/ out saving- inside of the Chrome browser application.
Not the best solution, but it's an effective "patch" for now.
I think the question was about to open a local file directly instead of downloading a local file to the download folder and open the file in the download folder, which seems not possible in Chrome, except some add-on mentioned above.
My workaround would be to right click -> Copy the link location
Windows + R and paste the link there and Enter
It will go to the file directly.
To open docs automatically in Chrome without them being saved;
Go to the the three vertical dots on your top far right corner in Chrome.
Scroll down to Settings and click.
Scroll down to Show advance settings...
Scroll down to Downloads under Download location: click the Change button and chose tmp folder. Then just close the screen.
Click on any attachments and a small box to the left will appear, it should automatically open if you click on it.
When the bottom left box appears it will contain an arrow; click on it and choose the option "Always open files of this type". Going forward it will open the file instantly instead of the small box appearing to the left and you having to click on it to open. You will have to do it just once for various files such PDF, Excel 2010, Excel 2013 Word, ect.