This game is so garbage that I wanted see how garbage it was.
The chest at the end of the battle has the chance to freeze randomly, making you unable to do anything. Refreshing the page would remove any buy-able x2 upgrades on the units that generate terror. You kept any upgrades you already bought but progressing would be near impossible because you don't have the x2 upgrade that you bought, forcing you to restart.
At level 36, the battle location name becomes an error. A few levels later, the image location becomes blank. At level 40 the game crashes and any attempt to start the game just crashes it.
The game itself is unbearably slow at the start and the just suddenly blows up when you are able to clear a certain level far later in the game. I would've liked it more if the deck just barfed the cards on me rather than show them painfully one at a time. Early battles are awful since the terror rewards aren't great and certain fights become a wall very fast. The card system is very slots like which was interesting but needing to buy the card for the multiply and duplicate bonus was meh. Then needing to fuse them together to use them was just another wall. New minions stopped at 15, but at that point you had all the skulls you needed which made all the the battles and grinding easy.
Overall, its a game with an irritating upgrade system, a battle system that was lackluster and time consuming to run thru, and an unfinished pile of trash with no payoff.
[A warning that it was incomplete or lacked an ending would've been nice.]