Gold, interest and streaks

Gold buys everything: units, shop refreshes at 2 gold each, and experience. Part of it arrives every round no matter what. The rest depends on how you play, and comes from two places: interest and streaks.

Interest rewards holding gold. At the end of each round you earn one gold for every 10 you hold, up to 5, so 50 gold earns the most interest there is. Holding gold early grows into far more gold later, which is why strong players rarely spend below the next interest step without a reason.

Streaks reward rounds won, or lost, in a row. From 2 in a row each round pays a bonus, rising to 3 extra gold from 6 in a row. A win streak also keeps your health, so it is the better one. But a loss streak with a full bank is a real plan, and it is where the cheap early health from the last lesson goes.

Gold is only worth what it turns into. Gold above the interest cap earns nothing more, and gold you hold when you are knocked out earned nothing at all. The game review flags exactly that: going out with more gold than almost anyone who finishes in the bottom four.