I was both wrong and confused when I wrote that. It is not always possible to jump off the board in this implementation when a stack is big enough to reach outside the board. A very simple counterexample is A2-A1. That puts a 2-stack in the corner. Such a stack has the range to jump off, but cannot be removed in the current Ludii implementation. That's a violation of the rules of the game.
But I confused this with a stack being completely stuck, i.e. not having any moves, which is a different question. That's the situation I vaguely saw was impossible.
Christian Freeling is great :) Emergo is one of my favorites.
Btw (since you mentioned Ai Ai), Lielow is also playable in Ai Ai. And the AI is much stronger in Ai Ai than in the Ludii player.
I wrote that .lud-file. There are 3 known issues with it:
(1) The identity of a player's king is only updated after their own turn, not after each player's turn.
(2) It is not always possible to suicide a stack that has the proper reach, because it might overshoot the mark (my code requires it to land exactly 1 step outside the board).
(3) Suicided pieces are not removed if the resulting state has no uniquely talles stack of the current player's color.
All of these issues are fixed in a new .lud-file written by someone else. (I usually write my own, but this is the second time the same guy has come to my rescue.)
But I confused this with a stack being completely stuck, i.e. not having any moves, which is a different question. That's the situation I vaguely saw was impossible.