So either starting out is really tough, or something's not explained well. It's been 3 straight days in which no one has bought anything from any of 5 booths. The "Make $1k in a day" achievement seems impossible.
Every night my mall is attacked by a crack team of well-equipped ninja (they have hang-gliders and personal helicopters) each of which carry exactly $20.
Annihilation (chance to deal 10% damage a boss by 10% of its max health and stun it for .5 seconds) should really be renamed "Decimation". Both are commonly understood to be synonymous with "destruction" but decimate literally means "reduce by 10%."
The "idle" tag is really misleading, since this is not a "set and forget" kind of game at all. At various points in the game you have to monitor your resources (and toggle things like mints and steamworks) on and off with some precision. Is there a way to get that tag removed?
I've now played floor 10 4 times, and each time the portal fails to appear after killing the boss (or after the guy who gives you the challenge appears.) Please fix.
So I finished the boss on Nightmare Level 0, and was told to go through the portal, but I can't find a portal. Is this a glitch, or am I just not noticing a portal somewhere obvious?
Expanding on what narutohidanlove was saying, I wonder how well tested the requirements (and move totals) are for the later levels particularly. A lot of the time it seems to require everything to break nearly perfectly to pass the requirement (hitting a combo on basically every turn, say). It seems like "more moves" or "a lower score requirement" in some cases would mitigate a lot of the frustration.
The later levels aren't tested as much as the earlier ones, so there might be a bigger variation in difficulty. However, at least 3 of my testers got 180 stars (we all did a lot of score/move/requirement tweaking together) and I had done lots of testing myself before this. It looks like a fair number of people have gotten 180 stars on Kong, too, so everything is possible.
Good example of impact luck has on this game. Level 39, have all but the top 2 blocks killed, but setting off the top bomb will pop them. I have a pink piece underneath the bomb, and a wild card next to the space above the bomb, and 5 moves. So all I need to do is keep popping that piece above the bomb until I get a pink one, right? 3 blue and one white piece spawn instead. Frustrating.
It really seems that if you trigger multiple spells at once, they should each damage blocking pieces/glass that the resulting blasts touch. It's disappointing when you trigger 8 spells at once and that blocking piece is still in your way.
One thing that would be really appreciated is after you fail a level, there's a "retry" button available right under the message that tells you that you failed. Having to click on the specific level adds an unnecessary step. Yes, you can restart a level when you have >0 moves left, but you should also be able to restart at 0.
Would it be possible to add a scientific notation option? Especially when the numbers get really big, it's a lot easier to parse in scientific notation (at least it is for me.)
 "Shop Empire 3"){kind=icon}
 "Shop Empire 2"){kind=icon}
 "The Perfect Tower"){kind=icon}
 "Cube Escape: Case 23"){kind=icon}
 "Caravan Beast"){kind=icon}
 "Destination Kepler"){kind=icon}
 "Galaxy Siege 3"){kind=icon}
 "Kittens Game"){kind=icon}
 "Blast Magus"){kind=icon}
 "Loot Heroes 2"){kind=icon}
 "Gunball Reloaded"){kind=icon}
 "Crusaders of the Lost Idols"){kind=icon}
 "World's End Chapter 2"){kind=icon}
Thank you very much for your suggestion. I will rename it in the next major update. :)