You've definitely got an interesting mechanic that needs further exploration, especially with that chain dying off and allowing the player to shoot the chain to disconnect "contagious" parts. I love this idea.
As probably mentioned earlier, the game lacks some polish. Fancier graphics, music and perhaps a couple tutorial levels to explain the mechanics in a meaningful way would be nice things to have as well as some kind of goals to achieve.
Good job on creating such an interesting mechanic!