Sonic Riders is great. I feel like it was unfairly hated when it first released because of a knee-jerk reaction to "Sonic on a hoverboard?!", focusing on that aspect alone, and then judging it by the quality of it's peers. Out of the 2000's third party era, it's honestly one of the few console games that actually holds up - Heroes is a slippery mess, 06 is... 06, and Shadow is Shadow, and Secret Rings doesn't play well until you've finished the game. Adventure 1 DX and 2 Battle both have their own issues - issues that still muddle their reception today. It was unique compared to other mascot racers and imo, was an incredibly solid racing game. It did have a difficulty curve to it with a ton of mechanics to understand: your air gauge, the slipstream mechanic, how ramps worked, tricks, the different racer types, all alongside dealing with the different track hazards they threw in there. But once you get over the learning curve? I feel like it rivals SaSASRT in terms of fun. Was it perfect? Not really - there's bugs, the story is pretty generic, the handling takes some time to get used to (it doesn't handle like a kart racer, handling closer to games like Wipeout), and the skill floor needs to be lowered some to help ease people into the game. I haven't played Zero Gravity (although that's on my list of games to play), but the original is fantastic, and it gets slept on because people think it's another Shadow. It's one of the few games I come back to every so often to play through and I honestly hope that the original gets remade in the future with online multiplayer.