I'm just starting with this idea, so it's just a small experiment for now.
It's only about state integrity, users can "reset" the chain by removing or modifying a block (will invalid the following blocks). It's also possible to do a weight attack by spamming the chain to create a derived chain from a previous point in history.
But it's easy to imagine having a room owner whitelisting players to accept their blocks and have tools to detect cheaters or trolls. For example, if you make a chest game (it's more realtime but any turn based game with only one opponent would do the same), if a player try to cheat by modifying his previous moves, the game will rollback at the position before the modified move, I find this intuitive.
I need to develop multiple experiments to see how well it can work. And optimize storage/computation, like batching actions in a single block instead of having 1 block per action.
Interesting to note that any change in the gameplay could invalid the previous blocks or simply update the whole thing like it was always here (I just added a salary system to the example without problems). This is definitely another way to conceive games/systems.