As much as I like to agree with suggestions. This one just doesn't work for me.
1. No context on how the game would work
2. Would get boring very quickly after realizing you are just playing a clicking simulator
3. Cubecraft doesn't need useless game modes like that. What cubecraft needs is more removed Java modes transported to bedrock.
If you want to play zombies.
1. Go to cubecraft skyblock.
2. Get to Island 5.
3. Enchant to port 3 or 4 on your leather armor to make sure you take less damage and sharpness 4 would also be good in making it easier to kill the zombies.
4. If you want to you can even make a zombie farm.
There you go, you are now playing zombies, and make sure to repair your leather armor and sword.