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STEP ONE: Download the file. Go to your email and open your Humble Bundle link. Towards the bottom of the screen you should see this:
Most computers are 64-bit, so if you don't know which one to download, use the 64-bit. Click the link and you should get a popup that looks something like this:
I've highlighted the box at the bottom that says "File name", because you can rename this file so you can find it easier later. In my case, here's what I named it:
"SlimeRancher0-2-3".
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EDIT TO STEP TWO:
Mike wrote:I just want to jump in and note that while Elskah's process should work fine, Windows's built-in Zip functionality should be able to handle the "Extract All" step without you needing to install WinRAR or similar. Right-click on the downloaded zip file and the popup menu should include an option for "Extract All" - After this, you can select a location and everything should proceed the same as above.
STEP TWO: Extract the contents of the ZIP. Go to your Downloads folder (or wherever you downloaded the file to) and open it up using WinRAR or a similar program (or see the above edit to extract without WinRAR!). I use WinRAR, so when I opened it, mine looked like this:
I (rather poorly) circled the "Extract To" button at the top. No matter what program you're using, it should have an "Extract To" or "Extract All" button like that. Select all of the files in the ZIP and hit Extract. You should get a screen like this:
At the top is the location it's going to put your files (in my case, that's C:\Users\(My name, scratched out for my privacy)\Documents\Slime Rancher). Make sure this is the same place where you installed your Slime Rancher the first time. (Using Documents\Slime Rancher is a good idea, to make it easy to find!) I put an arrow to the "Overwrite mode" box, because this is important! By default it should be set to "Ask before overwrite". If you're absolutely sure you're doing everything 100% right, you can set this to "Overwrite without prompt", but I usually leave it on "Ask before overwrite" just to be safe. If it's on "Ask before overwrite" when you hit OK at the bottom, a window like this should pop up:
This screen should show the location you're extracting the files to, as well as the file name "SlimeRancher.exe", saying that this file already exists. It should also show you the last modified date (mine is today, since I've already done this, but yours should be the date you installed Slime Rancher 0.2.2). If you're seeing this screen, it means you've done everything right! You can hit "Yes to all" (or do "Yes" one at a time for all the files, but that would take a while) and your Slime Rancher should be updated to the newest version. Your save files should be perfectly fine, so you can get back to playing right away!
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Google Chrome may flag this update as malicious software! This is a problem many users have reported recently. This is a fault with Chrome's security being too strict, NOT a fault with the file. If you're having this issue, try using Internet Explorer or another web browser to download the file instead.
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Feel free to let me know if I left anything out or if you have more questions! I'm happy to help :D I may also edit this topic every now and then as new updates come out and/or as more questions are asked and answered.