1) First download the GameCore plugin suite from spigot and demo maps from here.
2) Drop in the GameCore and GameLobby plugins as well with any games you want to add into your server's plugin folder.
3) Replace the default "world" folder in your server's folder with the lobby map.
Make sure to have the lobby's map name is 'world' or else you will have to change the name in the server.properties folder and GameCore's config file.4) Run your server to let the plugins generate their configs and files.
5) After the configs are generated, shut down the server and proceed to install the default maps by locating each plugin's config folder and putting the map in the 'maps' folder.
Maps should be as follows: Spleef uses Spleef_Default. Capture The Flag uses CTF_Default. Free For All, Team Death Match, and Infected use PVP_Default6) Start up your server and verify all is working correctly by joining each game.
7) Once everything is working and you wish to add your own maps, proceed to the Setup instructions to configure your games.