As mentioned in
this thread, here's a step-by-step guide on how to play Big Fat Awesome House Party:
1.
Download Flashpoint 11.1 Infinity or later. Note that version 11.1 was recently patched to fix some issues, including BFAHP not working properly.
Make sure to get the latest Flashpoint Infinity release even if you already downloaded 11.1 before.
2. Run the file you downloaded to extract Flashpoint Infinity.
3. Go to the extracted folder and run "start-flashpoint.exe".
4. Enter "big fat awesome house party" into the search bar and press enter.
5. Click on the Big Fat Awesome House Party entry and then on the blue Download button in the right sidebar.
6. After the game finishes downloading, it should start playing automatically. You can start it again in the future by clicking on the green Play button in the right sidebar.
Let me know if you can't run the game.
