No, the game is not compatible with Windows 8.1. Awesome 3-Card Poker isn't developed/updated yet to run on Windows 8.1. The game will run only on Windows NT, 98, Me, 2000, XP, and Vista, but there is a possibility to make it work via the Troubleshoot Compatibility feature. Right click the installation package and select Troubleshoot Compatibility. After the package is analyzed, Windows will display all possible tweaks available for this software. Select Windows Vista then let Windows run the program with the new settings or accept the configuration and then right click again the setup package and select Run as Administrator. If the setup starts normally, follow the instructions on the screen and proceed with the installation. You can start the application from the icon on your desktop.
There is also the possibility that the application will fail completely, in which case there isn't anything to be done due to compatibility issues.