Titanfall is already available for pre-load on Origin, and there’s actually a trick to play your copy early if you really can’t wait, disclosed by NeoGAF user Lunaniem.
All you have to do is to download a .exe and .par file modified from the beta here, then backup your original Titanfall .exe and .par files in a different folder. Finally replace them with the modified ones. You should be able to run the .exe and to activate it using your Origin account.
Lunaniem mentions that “as long as you have Origin running in the background, the servers seem to work.” You can also find further information and confirmation on Reddit. It’s worth mentioning that Respawn explained earlier that the servers will go up and down frequently leading up to the game’s launch, so service may be spotty.
As far as we could gather the files are safe, and Respawn previously mentioned that early players won’t be banned, but we can’t take responsibility if your computer implodes or your account is harmed by using this method.
Keep in mind that Respawn Co-founder Vince Zampella mentioned that the studio does not yet allow the streaming of the game before launch, so don’t.
Respawn is NOT ok with streaming the game yet.
It’s also worth mentioning that the game’s Producer Drew McCoy posted on Twitter:
I keep getting asked, but if I was in the position to use a modified .exe from the internet to play a game early… I wouldn’t.
Again, use this at your own risk, and if you do decide to use it, enjoy your early Titanfall skirmishes.