Yeaaa, zombies are weak for intentional, so players can enjoy the power of horde. For zombies slowing each other down, that's also intentional, since that's what I think a horde should behave when colliding each others in a horde.
Thanks for playing! I ran out of time, but I wanted to make enemy smarter by adding pathfinding.
*Zombies are dumb, so its intentional that they only follow orders and keep bumping to walls.