Please do the following in that Dell OptiPlex 790 so we can have more information about it:
Download and save the tsginfo.exe file.
After it's been downloaded and saved, double-click it to run it.
Information about your computer will appear.
Return here to your thread, then copy-and-paste the ENTIRE text here.

Windows 10 has DirectX 12 - which is backwards compatible with DirectX 11 and 10 and 9.
If your game requires DirectX 11, I don't know why it won't work with DirectX 12.
Someone else here may be able to answer that.

--------------------------------------------------

 

Please do the following in that Dell OptiPlex 790 so we can have more information about it:
Download and save the tsginfo.exe file.
After it's been downloaded and saved, double-click it to run it.
Information about your computer will appear.
Return here to your thread, then copy-and-paste the ENTIRE text here.

Windows 10 has DirectX 12 - which is backwards compatible to DirectX 11 and 10 and 9.
If your game requires DirectX 11, I don't know why it won't work with DirectX 12.
Someone else here may be able to answer that.

--------------------------------------------------

Please do the following in that Dell OptiPlex 790 so we can have more information about it:
Download and save the tsginfo.exe file.
After it's been downloaded and saved, double-click it to run it.
Information about your computer will appear.
Return here to your thread, then copy-and-paste the ENTIRE text here.

Windows 10 has DirectX 12 - which is backwards compatible to DirectX 11 and 10 and 9.
If your game requires DirectX 11, I don't know why it won't work with DirectX 12.
Someone else here may be able to answer that.

--------------------------------------------------

Tech Support Guy System Info Utility version 1.0.0.9
OS Version: Microsoft Windows 10 Pro, 64 bit, Build 19042, Installed 20200730192235.000000-240
Processor: Intel(R) Core(TM) i7-2600 CPU @ 3.40GHz, Intel64 Family 6 Model 42 Stepping 7, CPU Count: 8
Total Physical RAM: 8 GB
Graphics Card: Intel(R) HD Graphics
Hard Drives: C: 237 GB (145 GB Free);
Motherboard: Dell Inc. 0D28YY, ver A03, s/n /9JZZ5V1/CN7220024T02AZ/
System: Dell Inc., ver DELL - 6222004, s/n 9JZZ5V1
Antivirus: Windows Defender, Enabled and Updated

 

OS Version: Microsoft Windows 10 Pro, 64 bit, Build 19042, Installed 20200730192235.000000-240
Processor: Intel(R) Core(TM) i7-2600 CPU @ 3.40GHz, Intel64 Family 6 Model 42 Stepping 7, CPU Count: 8
Total Physical RAM: 8 GB
Graphics Card: Intel(R) HD Graphics
Hard Drives: C: 237 GB (145 GB Free);
Motherboard: Dell Inc. 0D28YY, ver A03, s/n /9JZZ5V1/CN7220024T02AZ/
System: Dell Inc., ver DELL - 6222004, s/n 9JZZ5V1

According to your log:
You have THIS Dell OptiPlex 790 Small Form Factor.

According to its support site and your log:
It was purchased in July 2012 in the U.S. and came with Windows 7 Professional SP1 64-bit.
Windows 10 Pro 64-bit was installed in it in July 2020 and has been updated to Version 20H2 Build 19042.
It has its original Intel Core i7-2600 processor (which has Intel HD Graphics 2000 integrated graphics).
It has its original 8 GB of DDR3-1333 RAM.
Its original 500 GB SATA3 HDD has been replaced with a smaller capacity 250 GB HDD or SSD.
It no longer has its original AMD Radeon HD 6450 graphics card - or - your log is not detecting it.
It has BIOS A18 which has not been updated to BIOS A22.

---------------------------------------------------

 

...
Its original 500 GB SATA3 HDD has been replaced with a smaller capacity 250 GB HDD or SSD.
It no longer has its original AMD Radeon HD 6450 graphics card - or - your log is not detecting it.
It has BIOS A18 which has not been updated to BIOS A22.

---------------------------------------------------

I have noticed that the log only shows the primary video card if there is an integrated one and a dedicated one so that may be why. You can confirm this by going to Device Manager and check what is under Display Adapters.

As to the issue itself, according to a Microsoft forum:

"The error message "DX11 feature level 10.0 is requires to run the engine" occurs when your computer doesn't have the required hardware feature. Another factor why you see this error is the graphics card driver issue, so you should make sure that your graphics card driver is working properly."

So we are looking at potentially a driver needing updating, or making sure we are using the correct video card. If we are not able to fix this, then the issue may be with the video card/s does not have the hardware features. Has this game worked before?

 

James:

GabrielleM did not submit a DirectX Diagnostic Tool image that has the "Display" tab selected, so it is unknown which graphics device and driver version are being displayed.

GabrielleM:

Can you do that please?

-------------------------------------------------

 

Here is the specifications for the game for reference.

Apparently on Steam, it's been release for Early Access Review since 2015

 

There are instances when some legacy DirectX components are not installed, and a game won't run and will show various DirectX errors. Microsoft provides a tool that updates the DirectX packages. The link to the Microsoft DirectX update tool is here: https://www.microsoft.com/en-us/download/details.aspx?id=35