Rings

Rings are important items inside sonic.exe spirits of hell, capable of doing various effects. In the game, there are 3 unique rings that you can collect, each with different effects.

Green Rings
Green rings are perhaps the most helpful rings. To keep the game short, it saves the user from a choice that would result in their death, either at the hands of Sonic.exe or something else. A valid example would be the choice between a red and green button in "It's Only Illusion" stage only. Knuckles in this choice has to pick between a red or green button. Red opens the door and allows him to progress. Green activates the crusher, killing Knuckles. However, it can be circumvented by having a green ring, causing Sonic to swoop in and catch the ceiling (like you imply to EXELLER when you or he rigged the green button somehow), giving Knuckles enough time to escape through the now open door. According to Dr. Egg man's assumptions, EXELLER is afraid of the Green Rings, causing him to lose control and allowing Sonic to help. The only choice where Green Rings don't play a role in is either Tails + Knuckles ending or the True Ending. Since there are no Green Rings in each respective level, one of the choices will always be wrong.

Red Rings
Red rings are one of the more dangerous rings, seemingly made by Sonic.exe himself. The red rings makes the victim suffer intense hallucinations as well as allowing Illusion to harm whoever absorbed the red ring. There are 2 types of red rings, both of which are covered in Illusion's page, but to keep it short, there is the imperfect red ring and the perfect red ring. The imperfect version only lasts a short time while the perfect version lasts longer.

Black Rings
The Black Rings can be both the least powerful and most powerful. Their effects only come in if you're the final one standing, A.K.A there is only one character alive. Without it's power, Sonic.exe will quickly end you, resulting in an automatic worst ending. If you do have a black ring, you will survive the assault, whether it be by gaining the power to retaliate, or simply by disabling his ability to harm you (at least temporarily), and by extension allowing you to get one of the "solo" endings, if that character survives the next level of course. Black rings are sometimes depicted as blue rings, such as in Whisper of Soul (when EXELLER finds 3 victims) and in the Help menu in character select of Spirits of Hell.