Messing around at the very beginning of Sonic 3, I took some time to scrutinize these quarter-pipe ramps in Angel Island act 1, and noticed some odd behavior: Spindashing up the curve, I am flung off at an angle, indicating that the final tile I touched does *not* have a flagged angle. (I did not hold any inputs while I was flung off) Walking onto the curve slowly from the top, Sonic remains standing perfectly upright and his horizontal movement speed is not impeded at all, indicating that he has an angle of zero. Corroborating the idea that Sonic has an angle of zero, jumping off of the slope in this state sends him straight up. The range where he maintains this zero-angle extends past the top tile of the curve, going quite far down (actually even farther than this video demonstrates) However, when sonic lands back down onto the slope, he immediately runs down the pipe, indicating a *non-zero* angle this time. I also checked in debug mode, there are no objects on top of the quarter pipe that could be messing with physics. This leaves a strange contradiction: when Sonic runs up the slope at high speed, or lands on the slope from a jump, he is angled as normal (not even snapped to 90 degrees, meaning this most likely isn't a case of a simple flagged tile), but when walking onto the slope from the top down slowly, he seemingly maintains an angle of zero. What is the cause of this? I did not see any discussion of this on the list of Sonic 3 bugs, although it did mention a different bug in quarter pipes where running at certain speeds will make him stop suddenly in the curve. Perhaps that is related? Edit: This behavior does not occur in the quarter pipes Sonic 1 GHZ; the edges of the slopes consistently act as steeply angled tiles in all cases.