Designing a game that sets the challenge up for the players at the right level is no easy task. I feel games should do a better job of letting the players choose the difficulty, that way veteran players can still sit around that 50% success mark without making it impossible for a group just starting. The game shouldn't really be easy as it takes away the need for the co-op element if we can all just go through the motions. Victory is all the sweeter when the 'doom' is on the very doorstep and we manage to help each other somehow pull off a big victory with seconds to spare. The doom needs to present itself as not only a steady flow but also show off that at any second it might snowball.
Snowballing doom is something that Red November does nicely but it is the domain of Pandemic and Defenders of the Realm where this is really prevalent and one of the reasons these games are fun to play. The players need agency to deal with the flow and to try and mitigate the threat of the snowball. Generally they need to have too many things that need doing to stave off the doom, so they need to prioritise the most doom-preventing actions. Thus the dooooom is always there and always mounting, but with a bit of luck and good choices the heroes can win the day.
Some more golemy sketches from last night: