My feedback for InverShift:
What the game does well:
Controlling the character feels good. The soundtrack is catchy and makes the game feel like a puzzle platformer as intended.
What the game doesn't do well:
The sound effects are loud. My first time making the character jump gave me a tiny jump-scare in my chair.
The gravity switch is instantaneous and is a bit disorienting. Every time I activated the gravity my perception of where my character was in the level reset; I had to pause each time.
It can be argued that flipping gravity is a way of inverting it inside out, but it didn't seem very strong an incorporation of the theme. I feel there's more you could have done there.
Areas of Opportunity:
To polish the gravity-flip action and avoid any disorientation, I recommend studying the level design of Mega Man X8's Gravity Antonian. Notice how everything freezes and the camera takes the time to rotate everything 180 degrees.
The only thing that gets affected when you invert gravity is the player. If your game's interpretation of the theme is inverting things inside out, one way you might be able to strengthen it is to create objects that change their behavior/function depending on the direction of gravity. (For example: a block can only be pushed when it is yellow).
I hope this feedback helps!