Mind the payment-channel case:
Parties
A
andB
lock the state of their balances,S0
, on the blockchain.A
makes a transaction by updating the state toS1
, signing it and sending toB
.B
makes a transaction by updating the state toS2
, signing it and sending toA
.
That can go on and on indefinitely. Now, suppose, instead of payment-channel, we're trying to implement a chess game off-chain. They bet $50 on the outcome.
Players
A
,B
init a new game on the blockchain and lock the board state,S
.Player
A
performs a move by updating the board state toS1
, signing it, sending toB
.Player
B
checksA
's move was valid, performs a transaction the same way.
That, again, goes on for a while. As soon, though, as A
performs a move that is clearly advantageous to him - say, capturing B
's queen - B
will just not sign anything on top of A
's move, forcing him to continue on the blockchain.
Does that mean that state-channels only work for transactions that affect the sender negatively?
B
will stop playing fairly, but what benefit does he get from this? He'll lose his money either way