Today I created the enemies, bullets and added collisions masks. 

I gave the enemy hp that decreases if it is shot.

I added a cool down that decreases my shooting speed.

When the main character is shot, the game restarts.

Later today I will add a background and more mechanics to the game to make it not boring.

Today I created a title screen.

I also changed the health points each enemy has and they change from happy to angry as they are shot.

I added background music.