Returns count of occupied role selection slots for given side. Players who claimed a slot in the lobby but did not start the mission are counted as well. If disabledAI = 0; in description.ext or Enable AI option is checked in Eden Editor, AI bots will be treated as valid players and will be counted too.
playersNumber returns playable AI as well as human players.
By default, a unit (placed down in the editor for example) ONLY becomes playable when the creator specifically checks the relevant checkbox.
In addition to the examples already given, this is how playersNumber can be used to get an array of players and playable AI on the same side as the side of the player: