A gameplay featured announced during the early development of the PC version of Diablo 3 has been absent from Diablo 3.
The runestones were originally set to do something similar to the Skill Rune system. These runestones however would allow you to inherit strange properties in different manners. One might allow you to imbue your melee attacks with fire, for instance whilst another one might make every Nth spell free. However, upon release of Diablo 3 on PC the runestones were nowhere to be found and many players assumed that they’d just bee replaced entirely by the Skill Rune system.
In a talk today at GDC 2013, Wyatt Cheng from Blizzard spoke about why they chose to go down a different route and use the controversial Skill Rune system. According to Cheng, having the stones in your inventory would have different effects on your skills and attacks, somewhat like having additional gear that just buffed very specific aspects of your character.
These runes, however, proved to be a “nightmare” since certain combinations wouldn’t work or didn’t make sense and occasionally wouldn’t do what the player expected.
After a lot of testing, the team opted to drop the runestone system in favour of the Skill Rune system.