TUNL Devlog
Notes on how a one-button cave flyer is built, tuned and kept fair. Written by the one person who makes it, with the numbers left in.
11 October 2026Reading the Instruments
A player could not read the icons at the bottom of the screen. Now each gauge says its name the first few times, shows its own rules, and has a one-screen guide.
9 October 2026A Shop You Can Read
The shop finally shows prices and what you get, and the rating request waits for a calm title screen instead of covering your record.
9 October 2026Same Cave, a Different Mix
More variety from sector 4 on without a single new hazard: sector motifs from the daily seed, a second soundtrack on the beat, and the numbers that show nothing got harder.
2 October 2026Every Press Is a Hop: Teaching a One-Button Game
Why most new players never found the control, how a press became a hop, and a tap circle that shows the beat without ever flying the ship.
2 October 2026A Star You Have to Earn
A Mario-style star earned by collecting, tuned by the share of a run spent as a star rather than by a coin count, and why it is a reward for deep runs.
2 October 2026A Power-Up That Leaves the Cave Alone
A laser that breaks boulders, added without changing a single rock in the daily cave: an old coin with a new label.
20 September 2026Seven-Second Sectors: How TUNL Paces a Run
Replacing a pile of difficulty curves with a plan: sectors, sawtooth density, hull scratches, and what simulated players said before and after.
20 September 2026The Same Ship on Every Screen
Frame-rate-independent physics, gravity scaled to the screen height, and a width cap: three separate ways a leaderboard can be unfair, and the fix for each.
20 September 2026Too Fast, Then Too Floaty: Tuning the Thrust
One constant, changed twice in a day after player feedback, and the ratio that explains why "too fast" and "too floaty" are the same problem.
20 September 2026A Three-Quarter View on a Flat Canvas
Drawing the ship in 3D with no 3D engine, under a hitbox the picture may not outgrow.
20 September 2026The First Two Months: TUNL from 1.0 to 8.0
The first eight versions in the order they happened, from a first commit on 5 July to a rebuilt title screen, and the audio bug that took three tries.
15 September 2026One Cave, Every Player
How a daily level is calculated from nothing but a date, and the two bugs that quietly forked the shared cave.
What the devlog is for
TUNL has a few unusual promises: a cave that is the same for every player on a given day, a ship that flies the same on every screen, and a difficulty that is measured rather than guessed. Each promise is easy to state and hard to keep, and most of the interesting work in the game is in keeping it. These posts are where I write down what broke, what I measured, and what I decided.
If you are here for the game rather than the engineering, the how-to-play guide covers the rules, the ships page covers the roster, and the changelog lists what changed in every version.