So this roulette wheel in Sonic Runners is the only way to get extra characters and companions (little creatures/objects that fly along side you and give you bonus effects). The golden egg on top that you only have a 6% chance of getting is the only one that lets you unlock a character. You can't get or buy any of these items separately either. The only way to get them is by spending red rings this roulette wheel.
You can get red rings by playing the game, but it'll take a while until you can get 50 of them. The other way to get these red rings is of course by paying for them with real money, and last I checked the amount you need to pay to get about 50 rings is somewhere around €4. So that's already a pretty big price for one spin of a roulette wheel that gives you a very small chance of a character you might want, and a big chance of a random companion that you probably don't want.
Of course, this is all a really shitty thing to put in just about any game, but what boggles my mind is that this somehow made it's way into a Sonic game. A game that's targeted at kids. It's almost as if SEGA is trying to make this happen. It makes me wonder if this is even allowed. Did nobody at SEGA point out that this is a terrible idea? I mean, this almost seems worse than trying to sell kids Sonic Boom: Rise of Lyric.