▶Once you expand the event window below, you can find Galaxy Quest.
And Galaxy Quest is one of the best ways you can get free coins.

If you select one of the Easy/Normal/Hard levels and clear all given missions, you can receive additional rewards.

The types of slots you have to play for each mission also vary, so you should always pay attention.

▶ You should first choose the difficulty.

▶ Then you can start your mission!

▶ If more info are needed:

[Important Notice]

If the quest meter is not filled to play the slot, it is necessary to check whether the quest is in progress according to the theme of the slot.