Other reviews already explained the mechanics, just keep in mind any and all elements besides match-3 have almost no depth or substance.

This could've been good, but the badly implemented city building, reliant on waiting for resources, and HUGE unintended difficulty spikes, even when playing on Easy, caused by bad map or boss design, make this a no-go for me.

When it works, it is good casual fun, but there are too many instances when it doesn't.

Conclusion: Could be good, but it isn't. Playtime is 7h55m, and I am way further 90% of the players.

Extra: Two note-worthy examples of difficulty spikes:

A map with tight corners and unusable center, making you have only two 1x3 options to match in order to attack the top monsters, with same situation at the bottom, forcing you to stock and spam consumables AND count on luck.

A boss that is only reachable by the tight center attacks, where gems are inside reasonably tight corridors, has big health pool AND summons barrier in front of him that extends far to the side, besides the usual monster summoning, forcing you to spam spells, consumables AND count on luck.

Only 7,5% of the players have beaten this boss as of now, I am not one of those.