> Fwiw nothing beats ‘implement the game logic in full (huge amounts of work) and with pruning on some heuristics look 50 moves ahead’. This is how chess engines work and how all good turn based game ai works.

For board games this is mostly true. For turn based games in general, it is not. It's certainly not true to say "all good turn based game ai" works like this.

Turn based games where multiple "moves" are allowed per turn can very quickly have far too many branches to look ahead more than a very small number of turns. On board games you might have something like Warhammer, or Blood Bowl where there are many possible actions and order of actions within a turn matters.

For computer games you may Screeps [2] or the Lux multi-agent AI competitions [3] which both have multiple "units" per player, where each unit may have multiple possible actions. You can easily reach a combinatorial explosion where any attempt at modeling future states of the world fails and you have to fall back on pure heuristics.

[1]https://en.wikipedia.org/wiki/Blood_Bowl

[2]https://screeps.com/

[3]https://www.kaggle.com/competitions/lux-ai-season-2