Undecember
About
Undecember is a PC and mobile cross-platform action RPG co-developed by LINE Games and Needs Games. Its core feature is a rune system that freely combines skill runes and link runes, letting you design thousands of builds with no class restrictions.
Season Structure
Undecember's regular content unit is "Season Mode." It is usually described as quarterly, but our measured median is 115.5 days — closer to four months than three. Entering Season Mode means starting a dedicated character in a fresh economy; at season end, characters and items move to the standard Eternal realm. What sets the reset apart here is what actually gets reset: with no classes at all, a character is defined by how you wire skill runes and link runes together, so a season restart is less about repicking a class than about rebuilding a rune layout from nothing. Season-only items, rankings, and a Season Pass sit on top of that.
How to Check Schedules
By weekday this is the simplest game on the list: all seven seasons we track opened on a Thursday. With only seven observations, though, read that as a consistent record so far rather than a rule. The median interval is 115.5 days — closer to four months than the three usually quoted. One disclosure: in July 2026 an incorrect end date in our own data caused this game's live season to display as 'ended' for a period. We traced the cause, corrected it, and added a check that catches the same class of error. If a status here ever looks wrong, trust the in-game display first and please tell us.
Season History
Undecember's Season Mode has run 7 seasons since 2024, and the 6 intervals derived from those seasons give a median cadence of about 115.5 days. Each season gradually widens the rune-combination build system at the game's core, and with simultaneous service in Korea and worldwide, it reaches a broad player base.
Who It's For
Undecember appeals if you want the freedom to combine runes into your own build without being locked to a class. It also suits players who like to move between PC and mobile, and those looking for an ARPG with a well-developed trading economy.