I'm trying to play the campaign mode of Supcom vanilla. I did go to the coop tab to launch my party.
When arriving at the FAF lobby interface in SupcomFA.exe, the "Launch Game" button is greyed out.
You need to check "Ready" next to the map preview to be able to start (even though you are single player, this is a multiplayer lobby and you can play coop with other people).
By the way, Aeon campaign is the hardest one.
@katharsas How I missed that, thank you.
Also, you have it set to "hard" difficulty. If you need to turn down the difficulty, you can do that by clicking the "options" button in the lobby.