2 ms·add '-windowed' to the launch options.by endlessvoid94 16y agoadd '-windowed' to the launch options.MikeCapone 16y agoHow do I do that? I'm not very familiar with Steam.rflrob 16y agoRight-click on Portal in the Library, then select Properties. Should be obvious from there.zweben 16y agoI'll just confirm that I had the same problem and doing the -windowed trick worked for me. Once you do it, you can switch back to full screen in the settings.