In Chrome, the game doesn't seem to idle unless it's in the active tab. It does idle if it's in a completely separate browser window, but not if I have multiple tabs in one window. That's a really bad bug for an idle game.
Locking the "Buy 10" button is ridiculous in the current settings. If it's unlocked, people who want to buy precisely 10 buildings can still do that, and people who want to use it as a "Buy max up to 10" button also have their way. If it's locked, the first group is basically unaffected, but the second group can't use it as they want. If you add a "Buy Max" button like you mention in the comment replies, it becomes irrelevant really, because the second group will use that one. However, if you add a "Buy Max", I'd much rather have a "Buy 100" button than a "Buy 10" button. It's really just a late game feature, and I would basically only ever use it to get everything other than oil up to the next achievement level without spending a ton of money by going over the limit.
The dressing system is poorly executed. As far as I can tell, there's no way to add/remove all the clothes of a set, and no way of telling what the perk of having the entire set does before you actually equip it. Combined with having to drag and drop every single item, the dressing becomes extremely tedious which ruins any fun of it completely. I like that you can customize the characters, but I don't want to spend 80% of my time doing it.
This game is pure awesome. I loved it for the level design alone, but what really gets me is how much fun it is kicking the spitting blobs around. I lost so many times just because I couldn't resist punting one of those things far off the screen.
The sounds are completely messed up, which is what makes this game require luck. It begins on level 3 where you get two volleys of arrows, yet only get an audio cue for the second one. This is possible to survive (though it means that you have to button mash block instantly every time you hear arrows), but on level 5 the sound cancelling just becomes ridiculous. The rider's taunting has the potential to cancel out every other audio cue in the game, and the archers and duelists are way too fast to be able to handle by skill from visual cues only.
To combat the prestige bug where the board prices don't reset, wait with prestiging until you see the "game saved" sign flash in the top left corner. When you prestige, immediately click the "buy new board" button to check if the boards have reset. If not, reload the game. This will bring you back to your last save point, which was before you prestiged if done quickly enough, and you can prestige again. Repeat this process until the boards have been reset and you won't have to lose your progress.
There needs to be some sort of bonus for starting waves early. At the moment, starting a wave early only hurts you because you won't get the cooldown time for your spells. Also, a hotkey for starting waves early would be good.
 "Idle Empire 2"){kind=icon}
 "AdVenture Capitalist"){kind=icon}
 "StrikeForce Kitty"){kind=icon}
 "MegaCorporation"){kind=icon}
 "Pursuit of hat 2"){kind=icon}
 "Water Knight 2"){kind=icon}
 "Mighty Knight"){kind=icon}
 "Hippolyta"){kind=icon}
 "Colony Age Robot Outbreak"){kind=icon}
 "Fishy Waters"){kind=icon}
 "Epic Boss Fighter"){kind=icon}
 "2048 Flash"){kind=icon}
 "Treasure Fusion"){kind=icon}
 "Idleplex"){kind=icon}
 "Dynetzzle"){kind=icon}
 "Paintball Racers"){kind=icon}
 "Dojo of Death"){kind=icon}
 "Sentry Knight"){kind=icon}
:D