Some guys in the official Discord really wanted me to add NPC support for joining games, so here it is!
Added NPCs support. This feature depends on Citizens!
Added a command to create a NPC: /sw createnpc [action]. The action could be either one of the values in the picture below.
Added teleportation canceling in spectator mode when players try to teleport to outside the arena.
* NPCs depend on the Citizens plugin. You need to spawn NPCs by using the command. To customize them, just use Citizens' methods.