You'll likely need to add an exception in Windows' security or simply disable it while playing.
Recent community posts
Gamepad support is not finished and is not expected to work at this time. If attempting to connect a gamepad has resulted in the game becoming unresponsive or crashing, deleting your Critical Chair save file should fix the problem. You can access the file in the same location as your vanilla Nuclear Throne save: /AppData/Local/nuclearthrone
It looks like there was unexpected data read in from your save file. Deleting the bad save file should fix the issue. It should be located in the same place as your vanilla Nuclear Throne save file; delete the file called "criticalchair[1.18].sav". Let us know if you continue having any issues.
Is it being blocked from downloading or blocked from running? If it's the former, try one of our mirror links:
Otherwise, it sounds like you may need to turn your firewall off temporarily while downloading.
If you have successfully downloaded the mod and your computer is blocking it from running, you'll probably need to make an exception in your firewall or turn it off while playing.