Just beat both Kingdom Valley acts. Act 1 is better than Rail Canyon but still inferior to Space Colony ARK. Act 2 on the other hand is the worst level in the game so far. There are barely any alternate routes to take, it's just very dull platforming without anything exciting, I'd say it's filler Sonic Colors act or Forces bad but at least those levels had the decency to end after two minutes.
Sidenote: I wish they added a reference to the vehicle sections you did in Shadow's Kingdom Valley in 06. Maybe have a crashed out GUN hovercraft in the water or have a stupid cutscene where Shadow sees a GUN hangglider, scoffs and then breaks out the wings, just anything
Also, once you beat Kingdom Valley you have the displeasure of rescuing the obese Down's Syndrome faggot known as Big the Cat. STOP FUCKING ADDING HIM TO THESE GAMES. NOBODY OUTSIDE OF A FEW TRANNIES ON R/SONICTHEHEDGEHOG (>FOUND THE MOBILE USER :OOOOOO) LIKES HIM. P.S. YOUR STUPID GAY FROG GOT EATEN BY ONE OF THE EAGLES IN KINGDOM VALLEY NOW GO KILL YOURSELF