When a player join's an expedition that's half-way done, they should be automatically given some coins, so that they'd be on an even playing field. A fair amount would be 100 coins per "Room", so that if they join by "Room" 5, they have 500 coins + their reserves to spend.
Otherwise they just start off with base weapons, and no boons, making them extremely inefficient for the rest of the run. Either coins, or perhaps an automatic weapons upgrade for both weapons to Green, depending on how far the expedition is.
Or, alternatively, if a player leaves, the amount of coins they had or even spent, could be held in reserve for the player that comes to fill that slot. This wouldn't be my pick for how to do it, but I rather anything than starting at "Room" 6 with 0 boons and base weapons.External link →