Can I install game into external SSD and play it on another PC with same steam account?

[iyFale Edvifin]

...my internet isn't super fast and I don't want to download hundreds of GB again

[Elucidator]

If steam is installed on the external SSD then yes.
but both PCs need to assume Steam is installed on that SSD.


Edit:
You can also set up a library on the SSD instead, but then you have to make sure the SSD is connected before steam is launched. It also comes with problems sometimes. The other PC may for example try to find the second library while the SSD is missing and this messes up Steam a bit. Its better if Steam is on the SSD.

[TheFamousPoundy]

yes, and steam does not need to be installed on that particular drive if you're using it as an external drive. For example if it's the D: drive and steam is on C: drive, its fine, you can add a download library on that folder via settings and steam will make a "steamlibrary" folder on that external drive and install games there.
you can then take this drive to another PC running steam, and add the library via the settings menu, steam will automatically detect these games installed on the drive and let you play them

[Elucidator]

This may also help:
https://help.steampowered.com/en/faqs/view/4593-5CB7-DC3C-64F0
but its basically an "Export" / "Import" feature for an existing library.

There are a number of ways at least.

[Jerry]

You can also install it into the regular folder on the quick internet connection, then copy the game files and the appmanifest file from the steamapps folder (if you are unsure, which is the right one, check the number in the shop page link) and transport it to the folder on your other PC.

That's what I do, when I am at friends or relatives with fast internet.

[Zukabazuka]

I remember you should at least connect the external drive before starting steam, Steam had trouble finding it if you connected it after starting steam.

[iyFale Edvifin]

Thanks for the tips and suggestions! I guess now I should get a new SSD

edit: can I leave steam opened and disconnect the SSD? (of course while outside of gaming)

[Callahan420]

Don't forget to copy the acf file.

[Jerry]

Originally posted by iyFale Edvifin:

edit: can I leave steam opened and disconnect the SSD? (of course while outside of gaming)

If you're doing it on the computer, that you only use for downloading, it will not do harm, as far as I can see. It would simply regard the games as uninstalled again. You should have copied the appmanifest file at this point already though, or your target PC may carry over that uninstalled status.
On your gaming PC, you definitely should not disconnect the drive while Steam is on.

Though as has been suggested, if you can afford the space, it is really better to have both Steam and the library on the same physical drive to avoid worries like that - either as Elucidator said, both on external, or going my way by copying it onto the internal drive and using the external just as a carrier.