Cool concept for a platform game, and a fun one at that!
The main mechanic, that separates this game from other platform games, is the scaling up the character. By eating mushrooms that can be dropped from either killed monsters or opened chests, your character will get bigger, which will increase your stats like jump power or attack range. It is a pretty interesting and unique idea, and seeing your character getting bigger as well as more powerful, is really satisfying! The movement and fighting controls are okay, they feel responsive, and are easy to understand.
The graphics are really nice. I liked the very detailed backgrounds and foregrounds, alongside the pixelart sprites. Although, the sprite of the main character isn't all that good. In my opinion, it is a bit too simple, and there are some weird artifacts appearing on it (like randomly placed gray/red squares). Also, in the third level, it was slightly difficult to tell platforms and backgrounds apart, since they were visually blending with each other.
All in all, it is a pretty fun to play platform game, with nice graphics, and an innovative idea!