First off, nice sprites. I love the unabashedly goofy premise, and I always like playing a villain or creepy character. :)
A few suggestions for improvement:
1. Sound! It really adds to the immersion. You can use programs like bfxr to generate old-school bilps and bloops. For music, you can borrow from a free-to-use collection (assuming you are unable to partner with a composer).
2. The enemies should flip to face the player. In practice, this simply means: If the player's X-coordinate is lower than the enemy's X-coordinate, set the enemy's scale to (-1, 1, 1). Otherwise, set it to (1, 1, 1).
3. A greater variety of enemies would help keep things interesting.
4. The text size needs to be larger, relative to the size of the game area.