Base Defense is a single/cooperative modification based on horde-style and RPG systems. It's awesome, you should try it ;)
Today I'm showing you working save system. It's server side feature, so you won't be able to load someones files on public servers.
For now it works with 3 commands:
saveprog - saves your current progress (it uses your nickname),
loadprog - loads your progress using our current nickname,
loadlast - loads last automatic save (autosave is triggered when player disconnects from the server, it will work for client crashes too, so you will be able to reconnect and continue your game).