Purchasing 200k cards consistently crashes the browser (Chrome). Since your game asks for really high quantities, perhaps a method that calculates large purchases differently. Like, if the odds for the card are .1%, when purchasing 10k you get 9-11. Afterall, at really high quantities random numbers become much more constant.
Once going for the next expansion, there is no play value, only idling. Perhaps a button that switches gains to an expansion only fund at an increased rate. Better yet, some mechanism that rewards interaction.
I was really hoping that maxed speed would make the zombies at least slightly faster than the humans, but sadly they still have to chase all the way across the world. If not adjusting speed, maybe add a slow to the infection.
Higher difficulties using coins to unlock is a bit frustrating. Didn't see that medium would cost coins until after I had spent enough of the ones earnable from achievements to make unlocking medium practically impossible. So I guess that's it for me, one playthrough on easy...
You probably have "Autobuy on manual prestige" enabled? This means it buys directly after you've prestiged, which could mean it spend a part of what you've prestiged for
While I really like the concept and most of the execution of the game, it is let down by the fact that the difficulty raises more than your upgrades help after a certain point. Ideally, people see the potential for more progress after getting an upgrade.
@alwindar It would be nice to be able to do the math on how much to invest vs spend in the event. However, in my experience, events in a game like this don't have an end date. They have a "Hey, we finished the new event" date.
With the ice trial weapon equipped, your shots get cancelled if you hug a north or east wall. When our backs are against the wall, we need as much help as we can get.
Humans and zombies both have reduced speed based on how much damage they have taken.