merging production items is not rewarding, as upgraded producers give fewer items alone than 2 un-upgraded ones can together. the shop is real money/gems only, there's no option to watch ads for additional energy or to pop any item bubbles, and production items don't recharge at all unless you FULLY depleted them last time you played. this means you might come back to the game after not playing it for an entire day, but you only get 1 or 2 items before having to wait another however many hours