transfer downloaded games to external drive?

Will downloaded games that require an activation code from another source be playable when transferred from external drive to main computer?
If they don't require activation code will they work when transferred?
I would like to be able to store my ever growing collection of downloaded games for easy retrieval instead of taking hours and hours to redownload.
Any experience with this appreciated

I think games from most companies allow you to save the installation files you download -- or at least the bulk of the files. But the best way to archive your games is going to depend on where you got them and whether you intend to play them on more than one computer.

With games from GOG and DotEMU, just save the installation files that you download.

With The Adventure Shop, save the files that you download. I think your computer remembers the activation even if you uninstall the game (unless you reinstall Windows or get a new hard drive). Games bought from Frogwares would work the same way. Activation information is stored separately from the game folder.

Gamersgate allows you to save most of the files needed for installation -- except for a small setup file that usually needs to be re-downloaded at the time of installation.

With Big Fish casual games, you can save the folder of the installed game. But if you want to play on a computer other than the one you originally installed on, you may end up having to re-download to get the games activated.

If a game requires the use of the registry, and makes registry changes during install, you need to go through the install procedure rather than just copying the game folder.

If you install games on an external drive, and then attach that drive to another computer where the games have not been installed before, it isn't predictable whether they'll all work. The Big Fish games will probably work as demos, then expire. Other games may need the registry changes that would have been made during the install -- and may not work at all, or may have bugs.

Hi Jenny.
I have transferred quite a few games onto my external drive, but I keep a list of the original place that they came from on my hard drive. The reason is that, depending on the place you originally downloaded them from, some games won't "work" unless the game folders are where they were stored originally on my main hard drive. In the event that I want to play any of them again, I alwayws know I can copy them back from the external hard drive to the place on my main hard drive because I DO keep a record of where they "belong". A couple of examples are: Games downloaded from Zodiac and from Steam will NOT "work" unless they are in the place where they were originally stored. Other downloaded games CAN be played from my external drive.
Sandy

I recently used the backup function in Steam to store files on an external hard drive attached to a network server. I also just did a manual copy and paste of one of the Steam games folder too. Both methods worked fine. Steam Backup Feature

If I remember correctly, I did not have to re-download any Big Fish games I transferred to another computer. I just had to reactivate them.

Amazon game installation files are easy to store. Just make sure you have any codes ready that you might need for a game activation.

Sanford, good idea to keep a list of where all the files should go. I usually store a notepad "readme" text with my install folders, reminding myself what steps to take and where everything goes. I also keep a spreadsheet of all the activation codes I might need again. That way they're all in the same place.

Jenny, when my sister had an older computer with less storage on her C drive, she used an attached external drive to install games to and ran them from it. There was usually no problem with that. Of course, as you say, moving that drive to another computer and trying to run the games again would be unpredictable.

Thanks everyone for your comments-I now have an idea of how an external hard drive works, which I didn't know much about before. I will bookmark this for future use.

Especially for extra large file games-for ex: yesterday I started downloading "Alice Madness Returns" and original Alice bundle from Amazon(a bargain for $7.49) then find out that you have to set up an account with Origin(EA Games) and provide a code # in order to download from there. Started at 9 AM and by 11 PM, still only 77% done, so went to bed figuring that it would finish and all would be OK. Wrooong! Got mssg "Downloader problem" so it was stopped.The game looked as though it was installed. but wouldn't play, so now I've uninstalled it.Will try again another time. AAARRRGGH##@@!!*&@
Well ya get what you pay for!