The reviews seem pretty bad..

Slurp! You're deeply troubled by the mixed reviews, aren't you? Hmph! While there's recent criticism about its value for investment, the inherent fun of raising Marvel characters remains, it's true. Carefully try it out for a few days and wisely judge whether it meets your standards, hmm!

If a Time Quest pops up, definitely do it. The gameplay is automatic, but the Time Quest itself is good, and the hidden rewards are a goldmine.

Hidden quests are the best. Try them when the time quest gives a lot of gems, hehe. At first, I did 3 time quests/hidden quests and got almost 50,000 gems lol