Signpost

In the 2D Sonic the Hedgehog games, the signpost is used to mark the end of a non-boss level. Their mechanic differs slightly between games. In the 3D Sonic games Goal Rings or other goal indicators are used instead.

16-bit

In Sonic 1, Sonic 2, and Sonic CD and their betas, a signpost appears to have Robotnik's face on it. Once you touch them and go right, they start rotating to the face of the character you are playing as. Upon completing this rotation, the zone ends.

In Sonic 3 and Sonic & Knuckles, the signpost falls from the sky after defeating a sub-boss. As it falls, you can jump on it to bring it back into the air for a 100-point bonus each time. Three spots on the screen hold secret monitors; if the signpost touches those spots, it goes back up into the air and the monitor uncovers itself. Once the signpost touches the ground otherwise, the act ends. Like with Sonic 1 and 2, it takes the face of the player you are playing as.

8-bit

Sonic 1, Sonic 2, Sonic Chaos, and Sonic Triple Trouble have the same signpost. It starts with a question mark. Once touched, it jumps into the air, spins, and comes back down with an icon indicating a prize. These icons change between games, but one is always the same: Robotnik, who gives nothing.

32-bit

The Knuckles' Chaotix signposts behave the same as those in Sonic 1. Unturned, they show a silhouette of Robotnik. Turned, they show the word CLEAR.