Plain cursor is the main mechanic that moves around. The cursor can glitch which is kinda weird anyway.
Clicking is how you start and move the cursor around, the controls are simple to use.
You click to change expressions which is a specific feature. The cursor sometimes feels like it is glitching.
Most quick tip is to use the cursor for simple tasks. The physics are wonky so it can be tricky.
Q: What are the controls? A: Clicking to change expressions is the stated control.
Q: What is the objective? A: Not stated.
Q: What is a stated feature? A: The cursor can glitch.
Q: What is the main mechanic? A: The cursor is the main mechanic that moves around.