Kortog
From Ratchet & Clank wiki
Kortog was home to Stratus City which was a city that was suspended high above the planet. It was part of Tachyon's empire and used to be the Educational District of the Polaris Galaxy before Tachyon invaded. This was where Clank got a power from the Zoni called the Robo-Wings. The city was full of robo-wing launchers that the player could fly anywhere in the city.
Stratus city was also the location of the Hall of Knowledge which was strictly off limits to trespassers'. This was where Ratchet and Clank discovered a Lombax planet called Fastoon.
The otherwise reddish color was probably let off by the number of red coloured architechture throughout the planet, along with amount of red-coloured gases seen throughout the cities.
