This game can be modified as needed, it can be a quick 5 minutes warm up activity or you can play for the whole class period.
Get students to close their eyes and the ALT and JTE will select students to be zombies.
Note: for a class of ~30 students, I usually pick 4 zombies to start. But you can modify the number of zombies depending on how long you want the game to last. I also tend to pick the most out-going and/or the students that are more comfortable with English to be zombies for the first few rounds.
introduce a question that contains that most recent grammar points.
For example: What would you like to do?
Provide sample answer where students can fill in the blank with new vocabularies that they've been learning. The "normal" students can answer with whatever they want, but the zombies will always have a specific answer (preferably something a zombie is likely to say).
Once the game starts, students will stand up and ask each other questions, if a "normal" student encounters a zombie, then they will be infected and become a zombie as well. Nothing happens if two "normal" students run into each other, same with two zombies.
For example: (Answer) I would like to ________________.
Normal students may say: I would like to play baseball, I would like to eat ice cream, I would like to watch a movie...
but zombies MUST say: I would like to eat brains. (sometimes I get zombies to say "I would like to eat you" and students go CRAZY for this, grabbing each other's brains and it's the funniest thing)
Introduce role: DOCTOR.
If a "normal" student manages to ask 5 other "normal" students, their role will be upgraded to DOCTOR. Doctor has the cure for zombies. So when a doctor meets a zombie, the zombie will turn back into a "normal" student. You can also introduce fun cue words for doctors to say when they reveal their identity. For example, if the zombies' answer is "I want to eat you/eat brains/drink brain juice", I often get the doctors to yell "NO!!".
The role of the doctor is great because it encourages students to talk with more classmates than just their friends, they are also less afraid of zombies once they become doctors. You can also modify the number of students they need to ask before they get upgraded to doctors, depending on how long you want the activity to be.
Start the game with a countdown. I usually do 3-5min per round. You can modify this depending on how many zombies you have and how many students they need to ask before they become doctors. The doctors are on the side of the "normal" students. So, when the time's up, if there are more zombies than doctors + students, then zombies win. And vice versa.