Not a bad little game. It did have a few issues, such as getting stuck like ereborn mentioned.
The attack works well, and it's nice to visually see the range of the attack as it goes out. The dodge/disappear mechanic is really good too! It is a little overpowered given that you can still attack while you're invincible though. The jump mechanic felt unnecessary though.
Getting more powerful over time feels good, but it would have been nice to have some indicator in the game when you absorb a monster's power. Some character animation, health bar blinking, sound effect, etc.
What the game seems to be lacking most is motivation for playing. The mechanics work well but there's no reason for the player to keep going -- no goal to accomplish, no end in sight, no backstory, nothing. Even something as simple as showing the number of monsters killed or distance traveled would give players an idea of the progress they're making. Never underestimate the power of a number that slowly gets bigger!