Good sprite work and controls! The camera was a little frustrating though, I felt like the only viable strategy was to run away constantly, but that also meant I had very little visibility on where I was running and always ended up smashing into a newly spawned cell that I didn't have time to react to. I think your reply in the other comment about killing cells when they touch the prison cells (maybe just ones that have been shot?) would've added a nice twist.
My best run got to 23 seconds left! No way I'm doing any better than that though.