Not true. Kelt-9b is the hottest planet in the galaxy. Kelt-9b has a surface temperature of 4600K. For reference the sun is 5800K and Mercury only reaches 700K. Kelt-9b is so hot because its star has a temperature of 10,000K and the two orbit extremely closely.

Edit: Sorry didn’t realize this is for a game. I’ll leave my comment though.