Unfortunately, no. This doesn't work with the Sega Game Room. To play your ROM you must open SEGA Mega Drive & Genesis Classics with the Simple Launcher.

I cannot tell you how, that would be piracy. If you have a Sega Genesis/Mega Drive cartridge, then you can get a dumper and dump the cartridge.

Anyways, let's begin.

First off, Make sure you have the latest release of PscdPack[github.com] on your computer.

Go to the game's directory and open the folder called "data", inside you'll have files that have the .PAK extension added to them. Copy one of them and paste it to the desktop, or anywhere in general and rename the .PAK file to any 4 digits, (e.g. 0089, 1909). Please make sure the .PAK extension remains intact.

Open PscdPack, and click on "New/Open". Find the directory your .PAK file is located and select your .PAK file. Rename the .PAK's title, and click on "Replace ROM". From there, choose your desired uncompressed ROM file and then click "Save", and then exit PscdPack. Drag & drop your modified .PAK file to the "data" folder.

Rename your uncompressed ROM file's extension to .68K and drag & drop it to the "Uncompressed ROMs folder" located in the game's directory.

Open the game with the Simple Launcher and your ROM file should show up in the selection.

Thank you all for reading! If this worked for you, make sure the mark this as helpful, and if you want you can give this guide an award. I'd be incredibly grateful.