My feedback for The Creatures from Inside:

What your game does well:
The game has originality. You illustrated and coded all of this and created something within the bounds of 'inside out' that few people would of thought of.

What your game is missing:
Once I picked up the gun the gameplay became repetitive. I was either walking through an empty screen, or I occasionally encountered a monster that dies in one hit if I click it. The game is missing challenge. While there is a pattern, without challenge to the pattern players will get bored and drop off.

The player character has a jump action, but I never found myself needing to use it.

Areas of Opportunity:
Giving monsters their own health bars, and giving monsters resistance to player attacks so they don't die in one hit are ways in which you can add challenge to the game.

Once you solve that problem then you can consider different kinds of monsters. Perhaps you could add a monster that requires players to make use of the jump action? (Jump behind them an attack from the rear?)

I hope this feedback helps!

I gave you a rating...