Developers of PC games, you’re getting kind of sloppy. Game installations have ballooned into drive-filling behemoths. Maybe 10 gigabytes for Far Cry 3 doesn’t sound like too much…until you add 67 gigabytes for the new DOOM, and 80 freakin’ gigabytes for Shadow of War. Pretty soon, even the most capacious drives start to feel a little snug.

RELATED: How to Save Space on Storage-Starved PCs With Windows 10’s “CompactOS”

If you’re tired of watching your free space shrink down to slivers, there’s a neat little tool called CompactGUI that can help. It gives an easy-to-use interface to the CompactOS function, a highly efficient compression tool that Microsoft introduced in Windows 10 (so, needless to say, CompactGUI will only work on Windows 10 systems). Normally, CompactOS only compresses certain files, but with CompactGUI, you can point it to whatever folder you want and compress the files within. It’s like the shrink ray from Honey I Shrunk the Kids…but perfect for your space-hogging video games. Here’s how to use it.

Step One: Back Up Your Game Files

Before you start this process, it’s a good idea to copy the core files of the game you intend to compress to a backup. The CompactOS functions works fine on most programs, but there’s a small chance that your game might take a performance hit due to the decompression function, or simply stop working altogether.

RELATED: How to Manually Back Up Your Steam Game Files

If you don’t have enough space for a full backup, then just make sure your game save files aren’t in the same folder as the installation files (they usually aren’t). You can delete a non-functioning game from your storage drive and re-download it if the compression doesn’t work.

Step Two: Download CompactGUI

An easy-to-use download for CompactGUI is available on GitHub. Click the link marked “CompactGUI.exe” to download the executable file. It’s a self-contained program; you don’t even have to install anything. Just double-click the EXE file to start the program.

Step Three: Run The Compression Tool

In the minimalist program window, click “Select Target Folder.” Now navigate to the installation folder for the game you want to compress. For example, almost all games downloaded by Steam are placed in a default folder, C:/Program Files (x86)/Steam/steamapps/common . For the sake of this demonstration, I’ll be compressing the massive installation folder for DOOM 2016, which is 67GB on my PC. Click the game installation folder, then “Select Folder.”

The program will give you a few options at this point. The four different compression algorithms are as follows:

XPRESS 4K: Fast compression with less space saved. XPRESS 8K: Medium speed compression with more space saved. XPRESS 16K: Slow speed compression with even more space saved. LZX: Slowest compression with maximum space saved.

This is a bit of a balancing act; the more compression you use on the game files, the more your CPU will be taxed in selectively decompressing them as they’re accessed (read: while you play the game). In general, use a lighter compression method for newer, more complex games, and a more aggressive algorithm for older games that your computer can run easily, and thus spare the CPU cycles.

The other options are pretty self-explanatory. You’ll want to enable “Compress Subfolders,” since some games keep all of their relevant files in sub-folders anyway. You might also want “Action on Hidden and System Files”—there aren’t any critical Windows OS files in your game folders, after all. “Force Action on Files” might be necessary if the program hangs or crashes. There’s also a “Shutdown on Finish” option, but that’s only practical if you’re applying the compression program to a massive directory and you’ll be leaving your PC for hours directly after.

Click the “Compress Folder” button, and you’ll see the progress bar begin. Depending on the size of the folder and the power of your computer, the compression time could be anywhere from a couple of minutes to an hour or so.

Once you’re finished, right-click the installation folder in Windows and click “Properties” to see the new size. Using the most aggressive compression setting for DOOM, I saved 18.2GB of drive space—enough for my entire Overwatch folder to fit into.

Some games will compress better, some worse, but users on various forums have reported space savings of up to 75% using this method. It’s definitely worth a try if you’re desperate for more storage space without paying for a new drive.

Step Four: Test Your Game

Now open up your game in the usual way and play it. Technically, it should be running slower, because your CPU needs to decompress the files as they’re being accessed. But the CompactOS system is surprisingly efficient, and since most modern games rely on the GPU to do the heavy lifting (and thus will be more limited by the GPU than your CPU), you probably won’t even notice the difference.

But this is a general process being applied to specific programs. A few games simply won’t run after being compressed, and a few more will take performance hits that aren’t acceptable to players, especially for fast-paced shooters and fighting games. If you’re noticing slowdowns or errors that you just can’t deal with, delete the compressed files and restore your backup, or just re-download the game.

Also, keep in mind that any new game files downloaded by updates won’t be automatically compressed. If you receive a major update, you may need to repeat this process.

Image credit: Bethesda, Disney-Buena Vista/Blu-ray.com