What I liked :
- Solid Mechanic : The fact that an hit cost you a plank.
- Readability
- Simple but good UI
What could be improved :
- Some polish (waves, water particles, plank that lowers when something is on it, etc...)
- Too much text introduction (It's nicer too introduce one rule, then test it, etc...)
- Some zombie pattern variations
- Zombie should kill you ?!
Hope it helps