What do you think is a good penalty for leaving games?
In Dota 2 you get some sort of "low priority", no idea what that means.
What's it like in LoL?
I think punishment for leaving is developer's fault, not players. Now what I mean by this bald statement?
There are a lot of heroes to play, crapton on spells, different play styles etc. etc.
New players will obviously want to try different things, but I know from my own experience, - if I'm stuck with a character I hate / do not know how to play what so ever, those 20-40 minutes suddenly becomes a burden. In this situation I just try to stick with a group, but I absolutely understand those who just leave.
This should be solved by the game, player A leaves, and those who are in a queue gets pop up window asking - would you like to play this hero, that was just abandoned by another person? If you say yes, then you're in a game right away, your level / gold is set to average of your team.
leavers could join new game with another hero of their choice,
group that just got dumped by one player gets new player immediately,
that player is automatically set to average level / gold of the team, so he's not useless (because let's be fair, usually those who leave are behind)
if you did accept an invitation to ongoing game, you're guaranteed 2x experience (assuming there's leveling system for your account)
next time you queue you're automatically put to the front of the queue
How about that?