Each time the engine writes or changes your game is a build: the first version, "make the boat faster", "add a storm". Your plan gives you engine credit, and each build uses what it actually costs to run. A typical build is about 22¢; a big game or a big change costs more, a small fix less. You always see roughly how many builds you have left. Prices include sales tax handling; payments are processed by Lemon Squeezy, our reseller.