Charge Run — a one-key dodging game for the Cardputer

§ 01 — Problem

A 240x135 screen, effectively one key of input, and a single piezo buzzer. The problem was fixing the core weakness of dodging games — risk with no reward — inside that envelope. A narrow screen leaves no room to add information, and every extra rule makes the game less playable.

§ 02 — Decision

I put the scoring mechanism itself inside the danger zone: the gauge fills only while you stay in an airborne charge band. When extending it, I avoided adding a second band and instead thickened the single one so charging accelerates toward the top — where the drones are densest too. The player still learns one rule; only the decision deepens, from "enter or drop" to "how high do I hold". Design calls were grounded in a knowledge base I built from Masahiro Sakurai's game design talks, checking each choice against principles like "tune risk by distance" and "return control after a mistake as fast as possible".

§ 03 — Learning

Level design would not fall out of arithmetic. Chasing a bug where the gauge never passed two segments, I found the cause was not a tuning value but the physics: the design premise of "staying inside the band" was not achievable in the implementation at all. After that I stopped trying to guess the numbers and instead built the instrument first — the two key values are editable on the device title screen, which also reports how many invincibility procs the last run produced and how long the first one took. Building something you can measure with beats guessing the right defaults.