It would depend on how prepared you are. I think it would be neat to have a "quick defense/horde" mode in the game. The game starts you off with a trader (in a trailer) and some building supplies/weapons. In 1 hour a horde will approach and in that time you have to prepare. Your goal is to keep the trader alive and continue building up the fort. The hordes would become bigger and deadlier with ever new wave. Each wave will last a specific number of zombies, and after the last one is killed, the 1 hours timer starts again. A plane will fly over with supplies, the trader will restock, you will earn Duke Tokens for the horde, skill points will be earned. This just keeps going until you can't keep the trader alive anymore. Eventually, you could be facing a ridiculously sized horde, but assuming the game is balanced, you may have several auto-turrets, 100's of spikes, steel reinforced walls,...etc. I think a mode like this would be a great way for people to practice defending against hordes, by understanding proper defense strategies.
Personally, I would like the game to go in a direction of having MORE zombies, but have them far weaker. For example, I'd rather have 5 zombies will low health and low damage, versus having what we have now. While on the subject, I'd also like there to me for variation in zombies, anywhere from activity, to aggressiveness. There needs to be a broader hierarchy of zombies. Have a ton of the lower level, weaker ones, but then introduce some stronger and faster zombies as you progress through the game.