This also makes it more difficult to have some kind of "diplomacy feature" in Huntercoin. If 2 hunters would agree to not attack each other and, should one still kill the other, automatically pay compensation to the victim (must be worth more than a hunter, different technical problem), how can the game engine know who attacked first.
For such a truce pact feature, you could just require that only one attacks the other. If both attack each other, noone gets any money. The compensation payment will give an incentive to the one who's being attacked to not attack themselves, so it should work out.
Yes, this would be the easiest way, and probably not gameable
I've actually thought a bit more about the issue here, and I think it might indeed be possible to use a delay here (as suggested by Bitcoin Co-Op). The idea is that we advance the game state only every N blocks, using all transactions confirmed in the last N blocks (considered to be at the same time). Then even if some miners do not like your transactions, you are fine as long as any one picks it, which should be fine unless a big chunk of the hash rate colludes against your transaction (and assuming the "attacking" miners are not actually in the majority and orphaning blocks just for this purpose). An issue here is that players are incentivised to wait until the last block in the time window, since then they can best react on others moves (but then it is their problem to balance this with transaction confirmation).
Note that I don't think any miner is actually attacking any players in this way - this is mostly theoretical.
Players would be incentivised to wait until they have seen the others moves, but to wait until the last block in the time window is a dangerous strategy. It would be a game of chicken, trying to make the opponent to reveal their moves.
But depends on the game. If moves are not simultaneous, like in most turn based games, then one side can have their move at block 10, 20, 30 etc, and the other side moves at block 15, 25, 35.