I'll list a couple of the main downsides.
I fell for the advertising banner, claiming it's a game in the style of Heroes of Might and Magic. But that's not true at all; it doesn't even come close to my favorite game.
The technical support is non-existent. I wanted to buy virtual currency, the money left my wallet a month ago, but it still hasn't arrived in the game. Support is just ignoring me; I can say I gifted them my money. (At least I only threw in 500 rubles.)
Endless bugs and server lags.
The game rules state that you can get banned if you haven't made any payments in the game for 30 days. They should have said right away that it's a subscription-based game, instead of telling fairy tales about it being free.
If anyone still wants to play this browser game, Google Shadowland Online; that's where our incompetent admins are stealing everything from.
