I notice that when playing the solo variant, it is legal to remove the final cube on the map belonging to the player. It is also legal (even in multiplayer) to remove the last cube of a Civbot. Does that mean the player (or Civbot) can never place another cube on the map? Expansion is always into an adjacent territory and without any cubes, no territory is adjacent.
Or am I missing something? The expansion action doesn't say that Navigation makes all territories adjacent to each other, it says "Civilisations which have Navigation Technology can expand into any territory." So can a new cube be placed somewhere on the map providing the player (or Civbot) has Navigation? Is that how a civilisation can be restarted?
On a related note, have I got the right interpretation of the Civbot's expansion rules? It has to follow the usual rules for adjacency and navigation. So before it has navigation it will look only at adjacent territories. After navigation it will look at all territories. First it will look at all empty territories or territories occupied only by cubes with lower military strength, and if there are any such territories it will place a cube in the highest numbered of them. If there are no such territories (i.e. everything is occupied by a cube from a stronger military civilisation) then it will place a cube in the highest numbered territory where it does not already have a cube. (Before navigation this can only be amongst the adjacent territories.)