The Battle Cats frequently has collaboration events (colloquialised as collabs) where players can earn cats called collaboration units. The cats are divided into six categories: Basic, Special, Rare, Super Rare, Uber Super Rare (commonly shortened to Uber Rare or just Uber), and Legend Rare (? Rare before you unlock one). All the cats change their appearance and gain abilities after being upgraded to certain levels (10 and 20 to evolve units from 'awakening' stages and 30 needing an external object such as Catfruit and evolutions ). The cats can be upgraded with XP to initially level up to the level cap of 10 and the player can eventually increase the cap to 20 + 90 for basic cats by levelling up their User Rank (UR) by upgrading cats, reaching milestones and using duplicate cats, and 50 + 80 for other cats using the same methods, however level cap increasing Catseyes allow the boost to 50 rather than just 20 (or 30 for these cats). All units in the game have a distinctive cat face, cat or cat shaped object/being somewhere on their sprite. Many cats may not look like a typical cat (and sometimes are not or are equipped with external objects like machines) or are characters earned in collaboration with other games. The cats are all unique in their own sense, design, and ability. The cats are the protagonists that the player deploys throughout the game. Uncanny Legends takes place even before Stories of Legend timeline wise, with some of the Legend cats you get from this chapter being indicated to be the ancestors of some Stories of Legend cats. The Stories of Legends take place within the same dimension of the three previous Stories, except it was back in time before the Legends/Legend Cats were sealed. There is also an additional category for scheduled and general event stages, and another category for Collaboration stages. The Legend Stages are further divided into two stories: Stories of Legend (SoL) and Uncanny Legends (UL), with the latter being unlocked after completing the former. The Catclaw Dojo contains a stage to test how many enemies you can kill within a given period of time, with an addition of some collaborated stages of the same premise, except with collaborated enemies.

The Legend Stages contain multiple stages filled with new enemies and some event stages (including collaborated stages). Additionally, it contains two extra chapters: The Legend Stages and the Catclaw Dojo. The Battle Cats contains 3 main stories: Empire of Cats (EoC), Into the Future (ItF) and Cats of the Cosmos (CotC). These enemy types also have cat units who can counter them. Enemies without a trait are considered 'Traitless' enemies. The enemies may have traits such as Red, Floating, Black, Metal, Alien, Starred Aliens (which fall under the Alien category), Angel, Zombie, Aku, Relic.

The gameplay involves sending a wide roster of cats out onto a 2D battlefield to defend the Cat Base. The Battle Cats is a tower defense game where the player selects a team of cats with different stat amounts to kill enemies to protect a base (called 'Cat Base'). English screenshot from The Battle Cats gameplay on iOS

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