Circus Caper is the title of a side-scrolling NES game where you control a young boy on a quest to save his sister who has been kidnapped by the circus. The game was released in 1990 by Toho Company Ltd. and received poor reviews.
You start out in the game with little life, and few weapons, but you can collect various icons to increase how many direct hits you can take, keys to open doors, along with various circus items to shot as projectives.
Many of the levels can be avoided all together by just walking backwards and back through the curtain from where you start. This will take you right to that level's boss battle.