So far Ive gotten Wacraft and Dayz working on it. Garrys mod and Counterstrike dont seem to fit well
You can try to force it via the system config.ini. I managed to get a few, whome refuse by doing it in the gamemenu, to work this way, but those I mentioned look strange and have an a-symmetric stretch.
Strange thing is, many old games work perfectly and the newer ones, which are soppesed to have eyefinity ,don't