IIRC, the Red Sphere, Blue Sphere stages in S3&K all required you to collect every one of the blue spheres on the stage. But I could swear I've had a few instances in Sonic Mania where I've finished a stage with blue spheres left in front of me. Do some of the later stages have surplus blue spheres?
Sonic Mania – Do Some Red Sphere, Blue Sphere Stages Have Extra Blue Spheres?
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Related Solutions
Completing a Blue Sphere bonus stage earns you silver and gold medals which unlock Extras and Secrets. There are 32 medals to collect in total to unlock every Extra and Secret.
Medals are carried over between playthroughs, meaning you can play though the game multiple times on different save files to get them all.
Unlocks
Secrets Menu
- 1 medal: Super Peel Out (from Sonic CD)
- Alternative to the Spin Dash which charges from a standing position.
- 7* medals: Insta-Shield (from Sonic 3 & Knuckles)
- Creates a shield to avoid damage for a split-second.
- 12* medals: & Knuckles Mode
- Replaces Sonic & Tails with Knuckles & Knuckles
- 16 medals: Debug Mode
- Allows object to be placed anywhere in a level
Extras Menu
- 20 medals: Dr. Robotnik's Mean Bean Machine (Puyo Puyo)
- Featured as the Chemical Plant Zone Act 2 boss
- Five different speeds to try
- Play against AI or Human in local multiplayer
- 24 medals: D.A. Garden
- Interactive visualizer and sound test mode.
- 32 medals: Blue Spheres
- Unlocks Blue Spheres mini game on the Extras Menu
- Selectable options for Original or Mania style
*Actual number of medals required may be less.
Accessing the Secrets Menu
To open the Secrets Menu, highlight the ‘No Save’ section in the file select in Mania Mode. The will now have a new button labeled 'Secrets'. (△ on PS4; X on Switch; Y on Xbox). Note that the Secrets Menu can only be used in 'No Save' mode.
Accessing the Extras Menu
The Extras Menu can be found at the bottom of the Main Menu below "Competition" and "Options". You can track your collected medals here.
Sources
- VG247: Sonic Mania cheats, unlockables and extras to return to the cheat-friendly spirit of the 90s
- Gameranx: Sonic Mania: All Blue Sphere Bonus Stage Rewards | Unlock Guide
- Eurogamer: Sonic Mania unlockables and cheats: Debug mode, Super Peel Out, Extra unlocks, Level Select and other secrets explained
- Destructoid: Did you know Sonic Mania has unlockable goodies?
- YouTube: WHAT HAPPENS WHEN YOU GET THE FINAL MEDAL IN SONIC MANIA?
- YouTube: Sonic Mania - D.A. Garden unlocked
- Nintendo Life: How To Unlock Mean Bean Mode In Sonic Mania
- Arqade: What is the D.A. Garden?
According to Eurogamer, collecting every ring in a bonus stage earns you a 'Perfect', which is required for getting a Gold Metal.
The trick to getting a Perfect is to collect every ring on a stage. You may notice you can finish a stage without collecting all the rings, despite seemingly collecting all you can see; that's because you can convert spheres into rings by creating an outline around groups of blue spheres. These can be squares or rectangles, groups that already have partial outlines already completed, or have unusual shapes, such as bouncing spheres cutting into the corners.
The trick, then, is to make sure you have converted all groups of blue spheres into rings before you collect any remaining individual blue spheres. The easiest way to do this is to leave behind one or two blue spheres that cannot be converted, getting the 'Perfect', then going back to those spheres you left.
It's worth noting that, as mentioned in our Sonic Mania unlockables page, getting all gold medals doesn't unlock anything in game - only Silvers is required. It's only if you want all Trophies or Achievements that Gold is worth aiming for.
Screenshot from Giantbomb's 'Quick Look: Sonic Mania'
Best Answer
You can definitely finish a blue sphere stage with some number of spheres still remaining. I'm pretty sure this is a bug, but I haven't found any definitive sources. I have seen people mentioning this on Twitter before.
I did find this reddit thread where user Domilego4 offers a theory: