By the way, is there any workaround to re-install these giveaway's if I ever have to re-install Windows or even install it to other systems?
Sometimes, specially at games.
a) If you downloaded a single setup.exe, just backup the unzipped folder (eg. c:\program files\mygame). Zip and put it somewhere.
b) If you downloaded 2 exe files (1 setup.exe and 1 activate.exe), (eg. alawar games), run the setup and with the last free version of total uninstall, trace (only the registry, not the file system) the activator (a registry writer), for the newly added registry entries. Export them on a file and back it up with the setup.
Although according to their eula, this is a completely legal process, it is for users with some experience, so if you need any details (screenshots etc.), please tell me.