There seems a little confusion on this around the net, so here’s an easy way to do it, after all it’s free money so you might as well, as it currently stands BTG is worth about $130/coin.
Currently there’s only a wallet on an android device for BTG called Coinomi so this is the way I’m going to claim mine, but I don’t have an Android phone, so what do I do? I use an Android Emulator on my mac.
Firstly you need to secure your coins, and separate it from the block that has your BTG. So we do this by making a new wallet, that has new private keys. Send the contents of your existing wallet to this wallet address, this will be your new wallet.
Now to claim the BTG. Close your new wallet, open the old one and extract the private keys. For example if using Electrum: click the Addresses Tab, scroll down through the addresses, find the >Change submenu, expand that, look for >Used submenu, expand that. On the used address, right click, and on the submenu click Private key, enter your password and you’ll be presented with your private key. Click the QR button to generate a QR code and take a photo of it, or copy down that address.
Now download an Android emulator, such as Nox, Andy or any other. Run the emulator, log into the Google Play store, download Coinomi. Open the new app and in it create a new Bitcoin Gold wallet. Once this is done, select it, click the three dots top right, and click on sweep wallet.
Now if you took a photo of your QR code, you can click the camera button and show your phone picture to the camera on your mac (in my case) or just paste/type your private key address into it. The wallet will retrieve your funds from this address.
Now send them to an exchange that is supporting BTG, like HitBTC, open an account, generate an address to deposit your BTG and send from your Coinomi wallet to it.
Then you can log out of the Android play store, delete the app and you’ve got your BTG sat happily ready to trade!