I think most of this can be done easily with the existing addons:
Additem event: only works once per player
This can be done with eventing. Just make an event like this (not correct events):
if variable hasrecievedsword~=1
on variable true - centerprint - "you have already recieved this item"
on variable false - set variable hasrecievedsword to 1
on variable false - additem sword
Magic spells: that require a mana amount with a mana bar
There is some kind of magic, but I don't think it has mana yet
Swords: that do more damage than default and less damage than default
There are tons of swords, use the search button. I think there is a good pack called RPG Pack or something
and health potions that heal you 150 health
Use pills, medpacks or events.
RPG inventory: A GUI that holds 30 items in which you choose which items are in your inventory making an RPG more easy
I think this exists as well, but not with 30 slots. I think 30 is way to much anyway. Add a bit difficulty by having the player choose between the items he thinks are most important.
