I was talking about local, not LAN. I've got a rig hooked up to the TV in the living room for these kind of games.
A balanced way to have players join/leave midgame would be my #1 request for a patch. In classic gauntlet games, it's as easy as just someone popping in a quarter, but in a game like this that has added progression, there would need to be a way for them to be scaled up.
On the other hand, it wouldn't be cool if this game adopted the Gauntlet: Dark Legacy branch of the game style, where they incorporated an element from Diablo: your character could be preserved independently of the game state, and you could join a game in progress with your saved character. That brings in all sorts of other balancing issues.
The balance I'd like to see is just for the game save to track every coin you collect from the start of the game. If I've been paying attention correctly, whenever you pick up a coin, it is cloned and put into ever party member's purse, so in a 1-player game, if you pick up 100 coins, you have 100 coins in inventory, and in a 4-player game, if you pick up 100 coins, each player still has 100 coins in inventory. If the total coin count was also saved, then new players who joined could just start with the same amount of gold as the existing player. Sure they won't have the purchased upgrades, but they'd be able to pick them up as soon as they came across a store.
Edit: Oh, and a way to change the player names in local would also be darling. It'd make it easier to determine which save state goes with which group of friends.