Steam games can't be executed in sandbox.

A. THE BUG/ISSUE (Varies from issue to issue)
Can you reproduce the problem & if so how reliably?:
Yes, always.
If you can, exact steps to reproduce. If not, exactly what you did & what happened:
1:Go to local files of any installed steam game
2:Manually launch game’s executable in sandbox.
3:Game will not run and after a few seconds you will be returned to steam client’s store page.
P.s. Same thing happens if you normally start any freshly downloaded game from steam client (unless already whitelisted).
One or two sentences explaining what actually happened:
Unrecognized steam game refused to run in sandbox
One or two sentences explaining what you expected to happen:
Unrecognized steam game would run in sandbox.
If a software compatibility problem have you tried the advice to make programs work with CIS?:
Not a compatibility problem.
Any software except CIS/OS involved? If so - name, & exact version:
No
Any other information, eg your guess at the cause, how you tried to fix it etc:
My guess : conflict with steam DRM \ defence. Games work fine if you “unblock” them

B. YOUR SETUP
Exact CIS version & configuration:
CIS 10.0.0.6086 default configuration
Modules enabled & level. D+/HIPS, Autosandbox/BBlocker, Firewall, & AV:
HIPS = off, Autosandbox = on, firewall = safe mode, AV = stateful
Have you made any other changes to the default config? (egs here.):
No
Have you updated (without uninstall) from CIS 5, 6 or 7?:
No
if so, have you tried a a a clean reinstall - if not please do?:
N\a
Have you imported a config from a previous version of CIS:
No
if so, have you tried a standard config - if not please do:
N\a
OS version, SP, 32/64 bit, UAC setting, account type, V.Machine used:
Windows 10 pro version 1607 build 14393.576 x64
UAC = default
Account type = admin
V.Machine = none
Other security/s’box software a) currently installed b) installed since OS, including initial trial security software included with system:
a=Malwarebytes Antimalware 3.0.4 Free b=Malwarebytes Antimalware 3.0.4 Free

Thanks for the report but compatibility in Sandbox is not guaranteed. It’s probably not a bug.

What do you mean? Isn’t sandbox supposed to safely launch any (unknown) program?

It depends on what is blocked. You should consider that a trusted application might use a method that is risky in a particular situation (and you might not want unknown applications to be able to do that). It’s not really meant for games as you will experience issues due to keyboard access, screen access, etc. Again, it depends on what is blocked but I don’t think it’s a bug in this case.

and yes, safely. Good word.

I don’t know… Sandbox is supposed to start applications in an isolated environment, it’s like it’s only job. If sandbox can’t start an application in an isolated environment, then it’s a bug.

That’s what I think.

Are you sure it doesn’t run? Maybe it closes silently by itself. There’s a difference.
Could you kindly check what is being blocked in logs? I’d recommend you to temporarily switch to proactive configuration before checking.

Thank you.

Actually, just remembered as I troubleshooted a similar issue, I did try game executable (from Steam) and it was running in Sandbox. This confirms my idea.

// attached screenshot

Ok, some corrections.

Not all steam games doesn’t run in the sandbox, some do, other crash \ close in a few seconds after starting, yet others crash \ close immediately after starting.

They seem to do the same thing in proactive and internet security (default) configuration.

Thanks. Makes more sense now. Anything interesting in logs?

No, just a bunch of processes being run virtually.

Just to ask, did you have any issues running these same games in the sandbox with version 8.4? If the games ran fine in 8.4 but don’t now, is because the sandbox has been “hardened” as the sandbox for version 10 imposes more restrictions for direct keyboard and direct monitor access. Also can you try with the proactive configuration to add HIPS rules for the troublesome games and set the allowed application predefined ruleset while keeping HIPS in safe mode so add the game and choose use a ruleset: allowed application, does it make a difference?

I don’t know if they worked in 8.4 sandbox, because at some point CIS 8.4’s sandbox got on my nerves, sandboxing every third app I started (and loosing progress on sandbox reset), so I changed my security to Comodo firewall only and regular AV (I know, less secure etc,etc.) and was using comodo sandbox manually to test suspicious files. I thought CIS 10 will be better, and it is, but now I have this problem with (probably) over restrictive sandbox.

Anyway if I will have to change HIPS rules (that is off in internet security config) I’ll just unblock steam games that I have problems with. I really doubt there would be malware in official steam games.

It’s not a bug as explained by futuretech. And I wouldn’t worry about that.
You shouldn’t experience issues with auto-sandboxing and Steam compared to older versions because file tracking is utilized. (Just remember to keep File List data if you consider a clean re-installation).