Quick setup
Install the game
In your Steam library, right-click BATTALION: Legacy and choose Properties. Open Betas and choose fps_challenge. No code is needed. Let Steam download the FPS Challenge version.
Startup crash fix
If the FPS Challenge version closes as soon as it starts, press Win + R and run the command below. Close Steam using its Exit menu, then open Steam again. The setting applies to your Windows user account, including other programs that use OpenSSL.
cmd /k setx OPENSSL_ia32cap :~0x20000000Play
In Steam, press Play on BATTALION: Legacy and choose FPS Challenge. Sign in with Steam, find a match and use the room’s connect button or copy its console command, including the match password.