While it may seem that there is very little information left for the development team to share with us, nothing could be further from the truth. Recently on Twitter, a user asked if there were any systems left to be unveiled for Diablo III. While the answer was short and to the point, it leaves plenty of room open for thought and speculation.
So, there is more than one more system that the Diablo team has up their sleeves to share with us as the development of Diablo III goes on. Perhaps the only one we know for sure is some form of trading system. There has been a lot of debate over the secretive system over the years. While we do know that there will be a shared stash for same account trades, we do not know how trading will work from player to player. Many people see the obvious answer in an Auction House. One that can be used to find buyers for your items while you are either battling the denizens of Hell or logged off and partaking in some RL activities. However, others would prefer an item based trade system similar to Diablo II. One where players meet up in games offering their Zod Rune for some Immortal King set. Either way, there is a lot to be desired in improvements from how trading was handled in Diablo II. Just how they are planning this system to work is anyone's guess for now.
Another possible system yet to be revealed is a mercenary system. In Diablo II, we had Hirelings that aided in our fights against the demons. Offering not only help, this system was perhaps one of the only real uses for gold in Diablo II. In the recent years when asked about the return of this system, the development team has remained surprisingly tight lipped. While never denying or supporting the idea, the fact that they remain silent on the issue speaks highly of some form of it returning. Many have hoped for an advanced customization and control over these helpers. While the old system allowed for a helm, chest and weapon to be equipped it is quite possible that they are extending this idea to a full armor set. Others have tossed around the idea of them having their own separate skill system. In Diablo II, there were some variations of skills the mercenaries had but each type was limited to one unique skill. Expanding this skill set could definitely add some customization to these followers. While we do not even know if this system will return, it seems more than likely that it will in some shape and we can guess just what form it will be.
Set items is one more system we have very little information about. Recently, the development team mentioned that the way they worked in Diablo II wasn't the best. Usually, by the time you got a full set, the items were obsolete. There have been a number of purposed ideas on how to change this system. Scaleable items so they remained relevant, higher drop rates of set items, a looser restriction or multiple items working for the same set. At some point, we will hopefully get some more information on how set items will work in Diablo III but for now we have to settle for knowing that they plan on them being end-game viable with rares, uniques, and crafted items.
Moving into the more speculative ideas, one system that was in Diablo II that has yet to return is the runeword system. While we do know that runewords will not be in Diablo III, this does not mean that there will not be some other system that will function similarly to help us customize our items. We do know that they have added enchantments through the Mystic. We also know that socketing and gems will play a much bigger role in Diablo III. However, none of this means that they haven't added yet one more way to help us make our characters distinct. In fact, a person offered the idea to Jay Wilson during Blizzcon about the order of gems being placed into items having unique effects. Jay's response was that the idea was possible and that he would talk about it with the development team. While this may not be the exact system they are using, it may be something that they were/are still looking into. After all, itemization and customization is at the core of the Diablo franchise and more of it could always be added.
There are of course several other systems that Diablo could include. What these other systems are remains a mystery at this point and open to specualtion. Minor or major, we all look forward to what this new year will bring us as far as Diablo III information goes.