The codex is a per-creature progression track. Hunt a creature and you fill a bar; fill the bar and you are paid in skills. Then the next rank of that creature's codex opens, costing more and paying more.
It is one of the more player-friendly systems in the game, because it converts routine hunting into guaranteed, visible progress that does not depend on loot luck.
How it works
Each creature type has its own codex entry with 25 ranks, plus a repeatable rank 26. Some entries cover a group rather than a single creature: the Thorifoid entry counts every Thorifoid and Thorio including the bosses, and the Halloween Creatures entry counts everything met inside the Halloween Mayhem instances.
Progress toward a rank is measured by what you spend killing the creature, not by how many you kill. That is why a larger maturity moves the bar further: it costs more to kill. In practice it means the bar responds to your cycle, so a more expensive weapon fills it faster per kill and no faster per PED.
Completing a rank pays skill points, and you choose which skill from a fixed list.
The reward at each rank
The system is regular enough to predict completely, which the community worked out and has checked from two directions.
Rank 1 pays your creature's lowest maturity health divided by 16, in PEC. A creature whose smallest maturity has 160 health pays 10 PEC at rank 1.
Every other rank is that figure multiplied:
| Rank | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Multiplier | 1 | 2 | 3 | 4 | 6 | 8 | 10 | 12 | 14 | 16 | 18 | 20 | 24 |
| Rank | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Multiplier | 28 | 32 | 36 | 40 | 44 | 48 | 56 | 64 | 72 | 80 | 90 | 100 |
The same multipliers are the cost: rank 25 takes a hundred times the cycle of rank 1. Two consequences are worth sitting with. Finishing rank 10 puts you 40% of the way through the ranks and about 9% of the way through the spend. And the multiplier is why people talk about "cheap ranks": the first several ranks on a new creature cost almost nothing compared to the last one on a creature you have nearly finished.
The skill lists
Which skills you may choose from depends on the rank, in a repeating pattern.
| Set | Ranks | Skills |
|---|---|---|
| 1 | 1, 2, 6, 7, 11, 12, 16, 17, 21, 22, 26 | Aim, Anatomy, Athletics, BLP Weaponry Technology, Combat Reflexes, Dexterity, Handgun, Heavy Melee Weapons, Laser Weaponry Technology, Light Melee Weapons, Longblades, Power Fist, Rifle, Shortblades, Weapons Handling |
| 2 | 3, 4, 8, 9, 13, 14, 18, 19, 23, 24, 26 | Clubs, Courage, Cryogenics, Diagnosis, Electrokinesis, Inflict Melee Damage, Inflict Ranged Damage, Melee Combat, Perception, Plasma Weaponry Technology, Pyrokinesis |
| 3 | 5, 10, 15, 20, 25, 26 | Alertness, Bioregenesis, Bravado, Concentration, Dodge, Evade, First Aid, Telepathy, Translocation, Vehicle Repairing |
| 4 | 5, 15 and 25 on some creatures only | Analysis, Animal Lore, Biology, Botany, Computer, Explosive Weaponry Technology, Heavy Weapons, Support Weapon Systems, Zoology |
The sets are not worth the same. For the same rank, a set 2 skill pays about 62% of a set 1 skill and a set 3 skill about 31%. Set 4, where it is offered, pays two thirds of set 3. So the multiplier table above is the set 1 figure, and picking Evade over Rifle at rank 20 is choosing roughly a third of the TT value. Whether that is a bad trade depends entirely on which skill you actually want.
Which creatures offer set 4 has never been fully mapped, and it has moved: a patch on 1 October 2019 took set 4 off rank 10 across the board while leaving it on rank 5.
Rank 26, the repeatable one
Rank 26 behaves differently from the other 25. Its reward is the same on every creature and for every repetition: 25 PED of a set 1 skill, 15.62 PED of set 2, or 7.81 PED of set 3.
The first repetition asks for 5,000 PED of cycle. Each repetition after that asks for more, and the reward does not change, so the return per PED falls the longer you stay on it. There is no cap: you can keep repeating indefinitely, at a worsening rate.
Why it changes how people hunt
Before the codex, choosing what to hunt was mostly about loot and cost. The codex adds a second reason to stay on one creature: your progress on it is banked, and switching creatures means starting a new track from the bottom.
In practice this means:
- Hunters specialise. Picking a creature you can hunt efficiently and staying on it is the normal pattern, rather than roaming.
- The reward is predictable. Loot is variable, but codex progress is not. A session that returned badly still moved the codex, and that is real value.
- Size does not decide it, cost does. Because the bar follows your spend, a lot of small creatures and a few large ones move it the same distance for the same PED. What separates them is the creature's own rank 1 figure, which follows the smallest maturity's health, and how cheaply you can kill it.
Picking a creature to work through
The considerations are the same ones that govern hunting generally, plus one:
- Can you kill it efficiently with the gear you have? See Choosing a weapon.
- Does its loot carry markup you can actually sell? See TT value and markup.
- Is it available somewhere you like being, at a spawn density that keeps you shooting rather than walking?
- And now: is the codex reward for it worth the number of kills it will take?
Where to look up a creature
Entropia Central's creatures wiki covers health, maturities and hunting data per creature, which is what you need to estimate cost per kill before committing to a long codex track.
You can also see what other players are actually killing and what it returns: the globals feed records loot events as they happen, and each creature's page aggregates the activity recorded against it.