Is it possible to let my friend play 'Life Is Strange' using my PC through teamviewer?

Family Share isn't an option?

You could just use Steam Family Sharing.

Maybe the delay will be bad at times. If you trust them enough to let them control your PC, why don't you do family sharing with her? You need to log into her account to allow it (through Team Viewer, possibly), but you'll only do it once, and she'll be able to play other games from your library too.

Family sharing. but you need to login to her computer

better use remote desktop if you manage. it's better

I mean, sorta. Teamviewer works, but it's highly dependent on connection speed. You could family share it, but if their machine can't run it, well, that's a problem. There are more efficient remote tools, like Window's integrated one, but obviously there are requirements of running the same OS. It will work, but it won't look great and there might be input delays if the network you have is really slow. Ideal solution is team viewer their machine, authenticate steam family sharing, and then have them download it and play though that.

Massive lag (i guess)?

The best option is to use family share, I've done it with 2 of my friends.

Log in her computer with teamviewer and put your steam login (in this way she can't see the password) and turn on the family share option :)

Family share is the best option to take, i share my games with my girlfriend all the time. All you need to do is simply log into her computer of choice either through loaning her the info (Only trusted) or just log in yourself, then authorize the computer. Once that is done, she can play the game herself and you could watch via steam stream. :3

http://store.steampowered.com/promotion/familysharing

Don't do it mate. Teamviewer is not stupid. Its non-commercial version is meant to be used less than 2 hours a day.

It will lock itself and until you delete its registry, its appdata folder and you change your IP, you won't be able to us it.

And yes, as mentioned above, unless you live in Hong-Kong or Tokyo, you will have enormous rates of lag

Was this her idea or yours?

I've tried Teamviewer for the same thing BUT other way round, my friend wanted me to complete some in-game quests for them through Teamviewer. Needless to say it was a pain in the ass just to connect, rendering issues, delays, bad colors due to laggy, slow connection, that person was on the other side of the world so yeah.. in the end, seeing that I got like 2 fps and considered it impossible to even move without actually knowing or seeing what am I doing, we decided it will be better for sake of sanity of both of us that I would simply log into their account and do the pesky quest for them on my own computer, which we did and it was done in couple of minutes and everyone was happy, something that would be impossible with Teamviewer! xD

Why not use family share? I do it with my baby sister so she can enjoy Life is Strange and she loves it.

I was stuck at a boss in a game and tried to do that with my friend so he'll deal with the boss for me but it was way too laggy, he couldn't even move properly. Maybe it was just because of bad connection, anyway you can try.
WHY CAN'T YOU FAMILY SHARE THOUGH, you got me curious ;-;

Why not buy them a copy of the game? You're friends and that would be a a friendly thing to do.