Space shooter.
- enemy life bars
- player hurt animation (shake or something)
- bosses
- bullets that explodes to a second bullet on impact
- background effect (moving stars, etc)
- time slow down effect (to escape enemy bullets)
- sound
- meteor fragments on bullet hit
2D art credit: http://www.kenney.nl from (https://opengameart.org/content/space-shooter-redux)