released a series of popular media-themed Stratego editions. Besides themed variants with substantially different rules, current production includes three slightly different editions: sets with classic (1961) piece numbering (highest rank=1), sets with European piece numbering (highest rank=10), and sets that allow substitution of one or two variant pieces such as Cannons, usually in place of scouts. Sets produced since 1970 or so have uniformly adopted the rule that scouts can move and strike in the same turn. Stratego AI In July 2022, DeepMind announced the development of DeepNash, a model-free multi-agent reinforcement learning system capable of playing Stratego at the level of a human expert. Related and derivative games Stratego and its predecessor L'Attaque have spawned several derivative games, notably two 20th century Chinese games, "Game of the fighting animals" (Dou Shou Qi) also known as Jungle or "Animal Chess", and Land Battle Chess (Lu Zhan Qi). The game Jungle also has pieces (but of animals rather than soldiers) with different ranks and pieces with higher rank capture the pieces with lower rank. The board, with two lakes in the middle, is also remarkably similar to that in Stratego. The major differences between the two games is that in Jungle, the pieces are not hidden from the opponent, and the setup is fixed. According to historian R.C. Bell, this game is 20th century, and cannot have been a predecessor of L'Attaque or Stratego. A modern, more elaborate, Chinese game known as Land Battle Chess (Lu Zhan Qi) or Army Chess (Lu Zhan Jun Qi) is a descendant of Jungle, and a cousin of Stratego: It is played on a 5×13 board with two un-occupiable spaces in the middle, and each player has 25 playing pieces. The setup is not fixed, both players keep their pieces hidden from their opponent, and the objective is to capture the enemy's flag.[2] Lu Zhan Jun Qi's basic gameplay is similar, though differences include "missile" pieces and a xiangqi-style board layout with the addition of railroads and defensive "camps". A third person is also typically used as a referee to decide battles between pieces without revealing their identities. An expanded version of the Land Battle Chess game also exists, adding naval and aircraft pieces and is known as Sea-Land-Air Battle Chess (Hai Lu Kong Zhan Qi).[3] Tri-tactics, by Gibson & Sons introduced in the 1950s combining L'Attaque, Dover Patrol and Aviation. The pieces represented fighting