CNCNet mods like Mental Omega can't count playtime towards RA2/YR by default. In this guide we will change that. The following is assumed in this guide:

1. That you have a CNCNet mod already installed and functioning.
2. That you have added it to Steam as a non-steam game.

Enter your mod directory, for example S:\Mental Omega. Create a new text file named steam_appid.txt. In that text file, paste the following number sequence: 2229850. Save the file.

Now, when you click the Play button in Steam for your mod, you should see Steam highlight Red Alert 2 and Yuri's Revenge. Your friends list will show you are playing it, and Steam will count playtime toward it.

Note: Mental Omega specifically uses MentalOmegaClient.exe to run. Some other mods, like Dawn of the Tiberium Age, close their launcher and use Resources\clientdx.exe as the main process. If your Steam UI says you're not playing anything when you in fact are, check which process is running and tie that one to your non-steam app.