The Golden City (TGC) 
A once beautiful city built by Athena centuries ago, where she hosted her games. Later on it was used by the triplets (Salem, Thorne, Ammon) and the Dark Beasts to host the Failed Games. Season 1 game's also started and ended there. Now it is currently used as a refuge for survivors.

Athena's Gate
The gate in the middle of The Golden City which took players to the games, once it was unlocked it eventually led to Arcadia. It has since been destroyed by Thorne.

The Guardians
Thea's creations (five of them), in which she used to guard The Golden City after Athena's death so that nobody would ever set foot inside The Golden City again. Each Guardian took one of Thea's powers, representing all five of them.

The Dark Beasts
The corrupted versions of The Guardians, which were corrupted over decades from the corruption inside The Golden City.

Arcadia
Another world where Gods live and rule. A pure world that is meant to keep balance for all existence.

Spirit Group
What players are assigned to in the game, a Spirit Group is the power they are given.

Corruption
A dark force that corrupts beings that are susceptible to it and destroys all things pure. Those that are corrupt tend to bleed black. Corruption was what eventually led to Athena's downfall and the start of Earth's descent when Athena introduced it to Earth.

The Flightless
Season 1 players that were rejected by Thorne / chose to come back to Earth.

The Alliances
Four groups that inhabit The Golden City, each having their own unique culture / views on everything.

The Wilds
The wilderness outside of The Golden City where non-alliance cats live.

Hostiles
Typically what those in the Alliances call outsiders.