It's one half of it; Lightning also needs a "time lock" mechanism to somehow execute payment for the committed balance of the channel if one party unilaterally abandons it. This is quite complex involving both parties holding a delayed and revokable payment from the other party.

In the case of a game, this might be simpler since you can have each player sign their own moves and the other player's last move, so that you can always broadcast your opponent's last move if they quit.

It's not too complicated on Ethereum. Here's some sample code, which Raiden devs have told me works much like their system.

http://www.blunderingcode.com/a-lightning-network-in-two-pag...

Yes, Lightning is similar, the previous blog post covers that. Plasma is a bit different, I'm still wrapping my head around it.