Those games are probably designed to run in Full-Screen mode. Many popular games utilize the DirectX™ technology to render 3D graphics. When these games are being played in Full-Screen mode (that is, not within a window), their graphics engine uses the DirectX technology to draw graphics directly onto the system's screen.
If you are trying to use the Splashtop app to play one of these games on a remote computer which is running in Full Screen, this situation will result in the Splashtop Streamer being unable to capture the desktop screen correctly through the Microsoft® Windows® screen-capture APIs. In this case, you would need to reconfigure these particular games to run in "Windowed Mode;" that is, to run within a window.
If your Windows is Win7(or Win8), and display is an NVIDIA GeForce graphics card with at least 512MB FB, you may be able to play games in Full-Screen mode, due to the optimization we made on them. Please check this link for more details.
If you are using multiple monitors with your computer and are unable to play with Full Screen, please disable the additional monitors. It may help.
NOTE: If your display already is NVIDIA GeForce but you still can't get a connection in Full Screen, please try this sequence again:
On the PC, minimize all applications or games which are in Full-Screen mode; then connect with the Splashtop app; and then restore the minimized applications or games.