So I'm just wondering how to transfer SimCity to a flash drive to play on my Laptop.I tried to copy it to one file but it did not work.
Easiest option is to reinstall the game TO the flashdrive, by mounting the drive then selecting it as install location. You should not need to remove your original install (just can not play it at the same time, if Steam-version).
Obviously if it is Steam or Origin-version it is going to need that software installed and running to start as DRM is enforced through its DLLs
While Richard's solution may work. If it requires registry keys, it will probably not work. Also you need to have no DRM on the copy. That means even when you bought it you need to crack it to remove the protection.
We're talking about SimCity though. If it's the latest version you should know that playing with cracked version will prevent you from going online.
Also while you could transfer the game you couldn't transfer save games via USB ( if you plan to use it on multiple PCs ). You have to copy most recent save files from the last computer you used and copy them again to user document folder to continue from the save game..
In short it's not worth it. Just buy it on Steam/Origin and install on the computer you want to use. That way your save files will be transported via cloud and you can continue from where you left off..