Coin Tower: Stack Merge

Core Game Rules
1. Coin Value Types
- 1 Coin: Low-value silver token, abundant on the platform, small single score gain
- 10 Coin: Standard drop coin, the only coin players can launch manually, medium single score
- 50 Coin: High-value rare token, spawns randomly on the grid, large score boost when pushed off
2. Drop Limit Mechanic
The "To add" counter limits how many coins you can launch per round; each tap of the launch button consumes 1 count. The counter refills after clearing batches of coins.
3. Physics Push Logic
Coins follow physical collision rules: falling coins exert forward pressure on stacked piles, creating domino-style chain pushes. Coins stacked behind fox statues require multiple drop impacts to shift free.
4. Assist Boost System
The bottom-right "Assist" progress bar accumulates percentage with every coin pushed off the platform. When fully charged, the assist skill activates, releasing extra bonus coins to help clear dense stacked piles.
5. Reward Currency (Bills)
Special paper bill tokens occasionally drop alongside coins, tallied in the top-left "bills" counter. Bills can be exchanged for permanent Assist skill upgrades and extra round drop limits.