Prepare to watch ads all day every day or pay hundreds of dollars for minimal progress. Everything relies on random drops. You need rare items, which can be obtained from watching ads. Each ad gives you a 10% chance at a rare item. There are 7 different rares. You need at least 40 of a specific rare for some upgrades. That means you need to watch ~2800 ads for one upgrade. Even if you pay directly for gems, you still can't buy the rares you need, and have to rely on randomized chests. AVOID THIS