Without a doubt one of the best 3D Sonic games ever made. It's an absolute joy to play, and one of the few games that I've put the time into 100%ing. It's not very long if you're doing the bare minimum, but running through all the levels, gunning for an S rank by acing your way thorough a tough shortcut at blistering speed is just so satisfying. Both the 3D and 2D levels are varied and unique in both aesthetics and gameplay, and don't get old easily. Unlike some other 3D sonic games, the levels are never just straightaways, but also have a clear direction of progression, meaning you don't feel like you're on rails, but you never feel lost . I love how many different paths and optimizations you can take to decrease your time or find secrets, it adds lots of replay value and makes getting those S ranks incredibly satisfying on both the 3D and 2D levels. The modifications system is also a great addition, giving you perks like a bubble shield or a higher top speed that let you customize Sonic to suit your playstyle or skill level. The missions aren't all fantastic, but they're a neat distraction, though there's no real reason to do them all unless you're gunning for a 100%. It also has an active modding community, with graphics and level mods galore. They even made a mod including all the daylight levels from Sonic Unleashed!. Overall, this is without a doubt the definitive 3D Sonic, and I can't recommend it enough to anyone who's a fan of the series, or wants to see how fun 3D Sonic can truly be.