This game has two types of bonus rounds and they are triggered the same way. There are two types of skeletons and when 3 or more identical skeletons appear anywhere on the screen, you'll play the bonus. Skeleton with gold is the scatter bonus and when they trigger bonus, you'll have to pick one of the coffins and they will reveal the amount of spins you'll play. Unfortunately they don't have any multiplier. The second bonus is triggered by skeletons in coffins symbols. You'll have to pick chests and they'll reveal your winnings. This game also has wild symbols, displayed as red jewels and they substitute for all except bonus symbols.
To be completely honest, the main reason why I like this game is the design and graphics, which in my opinion is one of a kind. The payouts aren't that great. Most of the time I play this game with 0.15$ bets because sometimes, when I've played with higher bets, the game has gone into a dry run, giving only dead spins. For me the free spins bonus is easier to trigger rather than the ruby necklace bonus, but the winnings never exceed 50x bet winnings. What I've also have experienced is when you can't get any bonus round for a while, it's better to switch the game, because when it's in a good mood, it gives bonus rounds often, when it's in a bad mood it will eat your balance fast.
Overall this is my favorite game from this particular software but it's just because of the looks. So far I haven't had any higher winings than 50x bet and judging by the paytable I don't think this game has big winning potential, so I wouldn't recommend to spend much money on this game because most likely you won't get anything decent back.