If you are not scared of the Editor I have a solution for you.
Create a New Module. Double click [Module] to get to the Module properties and name the game exactly the same as the name you see in the game list you want to join. To avoid a warning dialog on save go into Main Map and right-click on Map Boards to Add Board, leave the values on default. Save the module somewhere (not sure this is required). From the editor click on server controls and connect to the game. You will join the same room as the module you don’t have. You will ofcourse not be able to see any of the game components since you don’t have them, but chat communication should work. By default you will show up as “newbie” in the player list. You will have to first set a player name in the preferences before you join if you want to ‘be yourself’.