In that it says on the command line a game=mygameinfo where mygameinfo is a gameinfo class. I am guessing this has changed and is actually a GameMode class?
upon further checking, and looking at examples, it seems that it is how people set the GameMode to use, but how this is passed back into the game and picked up (specifically) in blueprints, does not seem to be documented.
Re-posting from a different thread I made on this topic:
the input to game needs to include the path to the class, and the . with repeat and _C there. That info was buried pages back in my search.
But to make it easier, you can go to your DefaltGame.ini and add something like this:
that creates an alias to the mode so you can just use game=DM in that instance and it loads the proper mode when loading the level.
(L_Deathmatch being my game mode BP, yours will differ)
would be cool if you all updated the documentation with this sort of info instead of the old GameInfo reference.