Steam on Chrome OS kills dreams of simple modification.

One of the most interesting things about covering Google's technologies and products is how communicative the company can be when explaining how things work. It recently kicked off the first part of a planned series illuminating how it finagled Steam onto Chromebooks. In this first high-level overview of the technologies involved, one key fact has already been detailed: Modifying games (even just to tweak configuration files) might be pretty hard, if not impossible.

As usual, Chrome OS's virtual machines (VMs), and they're a big part of how Steam works on Chromebooks. If you remember sites like ours throwing around the name "Borealis" in reference to Steam, that's the name of the VM image that Steam runs in (which is based on a modified version of Arch Linux, and probably a nod to the Aperture Science ship referenced in Half-Life 2: Episode Two). This VM, like Chrome OS's other VMs, keeps things simple and secure — everything you need for Steam to work is contained right there in that VM, it can be installed (and uninstalled) all at once, and it never has access to your files or system directly. Google even built its own Vulkan virtualization driver to reduce the performance overhead associated with using a VM for games.

VMs are great for security, but, paired with what else we know about how this one works, it might introduce a bit of a headache for gamers hoping to install mods or even just tweak their games to work better on their Chromebook.

To enhance security, the VM image is used in a read-only state and subject to validation. Our own testing indicates that this includes some form of verification to ensure it hasn't been tampered with. I'm told by AP's Kent Duke that it's "so tight that even updating to a platform higher than what DLC expects (i.e., from Dev to Canary) prevents the VM from booting," and the software tools it has are limited. (For those in the Linux know, you can't install software to the VM via tools like Pacman, there's no Sudo, su is locked, and text editors aren't available.)

These limitations collectively mean that, so far as we know right now, there's no way to write to the VM image to make modifications to game files. Furthermore, even if you were somehow able to modify the contents of the VM and game files through some sort of exploit, it's almost certain you'd break the Steam VM entirely by doing it.

This might sound like a very "whatever" issue that only hardcore game modders hoping to add Thomas the Tank Engine to Skyrim would care about, but there are actually plenty of reasons you might want to change a game's configuration files. Often developers will bundle in extra non-user-facing settings in separate configuration files that can help you eke out slightly improved performance — handy when playing on underperforming hardware (which Chromebooks sometimes qualify as). Chromebook hardware also varies a lot when it comes to things like display density, and games aren't always built to take details like that into account. Occasionally that can be addressed by tweaking a game's configuration files or launching it with a specific parameter attached if there isn't a user-facing setting for scaling in the game itself, but that's not possible here.

Of course, games themselves can address these kinds of issues in their own ways by loading menus with additional settings, but that's unlikely. This limitation strips away one of the concrete advantages of "PC" gaming — even if it's on a Chromebook. Workarounds may yet be discovered, and some of us here at Android Police have been digging to see what is possible within the limitations of the VM framework.

This probably won't outright kill mods for games on Chromebooks since Steam has support for mods through the Steam Workshop, but it does mean you may not have all the same modding freedoms you would on a "normal" PC when it comes to tweaking games — at least until someone finds a way around Borealis's verification system.

( Details and picture courtesy from Source, the content is auto-generated from RSS feed.)

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