Add these lines into de app plist:
```
    <key>LSApplicationCategoryType</key>
    <string>public.app-category.games</string>
    <key>LSSupportsGameMode</key>
    <true/>
```
Then cd where the app is located and run this command:
```
codesign -f -s - "Aplication.app"
```

Now the app opens in game mode