My snake has been winning matches! Still losing more than it's winning, but it's doing well for two days development!

Strategic next is prediction. My current biggest cause of death is head on collisions that could have been avoided if I'd had even one more turn lookahead, but I don't want to stop at one turn. I've got maybe 300ms to play with, that's plenty of time to explore a biggish tree.

Brute force suggests that each turn generates 4 (snakes) * 3 (possible moves that aren't instant suicide) = 12 possible next turn states. That goes up with the power of the number of turns, so 12, 144, 1728 for the next 1,2, or 3 turns.

I need to decide/work out what sort of data I want out of the algorithm. I don't want to run my full heuristics for each snake, because I can see that my design choices are different to other snakes.

As an early efficiency, I'm going to ignore any snake who's head is at least (max depth + 1) squares distant, as they shouldn't be able to cause trouble in the planning horizon.

Then, for each remaining snake, calculate the list of non-suicidal moves.

I'll add a little bit of weighting here, e.g., a positive weight for a winning head to head, a negative weight for a losing one, small positive for carrying on in the same direction.

Then resolve the 'best' move for each opponent, breaking ties towards messing with me.

Push that state onto a stack, and calculate my move for that new state.

I'm not convinced. I think what I want to end up with is the chance that there's going to be a snake in any given square, adjusted for how many turns of lookahead I've got time for. Then, my snake should pick a path with the smallest chance of encountering another snake, subject to the rest of the weighting.

If it's just me on one side of the board and opponent on the other, then it's a big sea of zero probabilities. If I'm right up close to someone else, then there's something like a 1/3 chance to encounter another snake (and I'd hope to not get into that position).

I'll have another think/play in the morning.