http://warlight.net/MultiPlayer?GameID=3846248

Can you force join a player in the Seasonal Ladder? I haven't read settings and I will check them now to see whether it tells me the answer to my question but I hope I can force join - I want to play more games, not have this one sitting on my game list, contributing nothing to my rating.

It's allways possible to force-join tournament games after you have been waiting on the opponent(s) for a longer time since the game was created than the direct boot limit.
E.g direct boot is 3 days, after 3 days waiting on your opponent you can force-join.

I believe it works the same way whit ladder games, but I don't know for sure.

you cant force join in any ladder game, because the auto boot is at same time as force boot then the auto join is same time as force join so it will automatically do it for you