Cave Flyer: a one-button game in Games by Zaweba
Cave Flyer in Games by Zaweba is a one-button 8-bit flyer: hold to climb, let go to drop, and thread your craft through a narrowing cave.

One button is all Cave Flyer asks of you. Hold it and your craft climbs; let go and it drops. Out of that single control the game builds a test of rhythm and nerve, as you thread a small craft through a cave that keeps getting narrower and faster. It's on the Retro arcade shelf of Games by Zaweba, drawn in the style of an 8-bit 48K home computer, and it's one of the quickest games in the collection to pick up.
The goal is distance. You fly as far as you can without touching the walls or the rock pillars, and you grab crystals along the way for bonus points. That's the whole game, and it's a good one to show to someone who has never played anything on the retro shelf before.
Picking your button
Any of several will do. Space, Z, Up or the mouse button all make the craft climb while you hold them. That choice is more useful than it sounds. Some people find a held key steadier than a held mouse button, and others prefer the mouse. Try a couple of runs with each and keep whichever gives you the finest control.
Flying in a rhythm
Because the craft is always either rising or falling, you never hold it still. Steady flight comes from short, regular presses that keep it bobbing within a small band, rather than long holds that send it shooting up and long releases that let it drop away. Think of it as tapping out a beat rather than steering.
When a pillar or a change in the cave appears, adjust that rhythm early. A gentle climb started in good time is much easier to control than a sudden full hold at the last moment, which tends to overshoot into the roof. The same goes for coming down: let go a little before you need to, not at the last second.
A cave that tightens
The cave narrows and speeds up as you go. At the start there's room for slightly sloppy flying, and that's the time to settle into your rhythm. Later, the gap between roof and floor shrinks and things come at you faster, so small movements matter more and your presses need to get shorter to match.
Crystals are a temptation. They're worth bonus points, but a crystal tucked close to a wall or a pillar can lead you into a crash. Take the ones on your line and leave the risky ones, at least until you know the cave's pace well.
Why it suits a short break
A run of Cave Flyer can be over in seconds or last a good while, and starting another is immediate. Esc pauses if you need to stop mid flight, and F11 makes it full screen, which gives you a bigger view of what's coming. The title card and F1 both explain the controls if you're showing someone else how to play.
Games by Zaweba records your best score and how many times you've played, on your own PC, and shows your best next to your score when a run ends. With a simple measure like that, it's very easy to say just one more go. You can star it as a favourite so it's easy to find again, or press Surprise me when you've had enough of caves and want the app to pick something else.
Like everything in the app, the cave and its sounds are made in code, so there's no download, no account and no adverts between runs. Keep your presses small, stay in the middle of the gap where you can, and only chase a crystal when it's already on your line.