CNK Challenge

A CNK challenge in Crash Nitro Kart means the player must collect the letters C, N & K and come in first place to win a CNK Token of a specific color. Once all CNK tokens of one color have been collected, the player can enter the corresponding gem cup. For example, collecting all red CNK tokens unlocks the Red Gem Cup.

In the Nitro-Fueled remake, these have been changed to CTR Challenges, likely due to it being marketed as a Crash Team Racing remake despite having Nitro Kart tracks.

Red Gem Cup

 * Inferno Island
 * Meteor Gorge
 * Assembly Lane

The Red Gem Cup is unlocked by collecting the red CNK tokens in Inferno Island, Meteor Gorge, Out of Time, and Assembly Lane. Winning this gem cup unlocks Dingodile.

Green Gem Cup

 * Jungle Boogie
 * Deep Sea Driving
 * Out of Time

The Green Gem Cup is unlocked by collecting the green CNK tokens in Jungle Boogie, Barin Ruins, Clockwork Wumpa, and Android Alley. Winning this gem cup unlocks Zem.

Blue Gem Cup

 * Barin Ruins
 * Clockwork Wumpa
 * Electron Avenue

The Blue Gem Cup is unlocked by collecting the blue CNK tokens in Tiny Temple, Deep Sea Driving, Thunder Struck, and Electron Avenue. Winning this gem cup unlocks Polar.

Purple Gem Cup

 * Android Alley
 * Tiny Temple
 * Thunder Struck

The Purple CNK tokens are obtained in a different way. The player must enter the battle arenas; Temple Turmoil, Frozen Frenzy, Desert Storm, and Magnetic Mayhem to obtain the crystals in the arena before the time runs out. If the player is successful, he/she will obtain a purple CNK token. Winning this cup unlocks Zam.