Thank you for playing and for the feedback!
I can see how the zombies could be mistaken for the soldiers so I get why that could happen, and there is a knock back mechanic, but it's scaled with damage so if you can get enough upgrades to your damage from the power ups you can do more knock back but I can also see how it would be hard to tell at the beginning.
I'm glad you enjoyed it and thought it was fun though!! :D