One button, one helicopter, one ever-tightening cave, hold to climb, let go to drop, and feather the gaps as long as you can.
Your helicopter flies forward on its own; you only control lift. Hold to rise and release to fall, threading a wavy cave that narrows and speeds up the longer you survive. Touch the ceiling, the floor, or any jutting block and you crash. Collect green fuel cannisters to fill a small hover reserve you can spend to freeze your height for the tightest gaps, plus coins and a brief shield along the way. Distance is your score.
Copter Cave is a nod to the one-button cave flyer, a form that spread across the early web and early handhelds around the turn of the 2000s, SFCave being one of the early versions. It was folk software: rewritten endlessly, rarely credited, and usually no more than a few kilobytes.
The whole game is one input. Holding rises, releasing falls, and there is no brake, so a craft is always accelerating in one direction or the other and flying level means alternating constantly. The cave narrows as you go and the speed climbs, which means the corridor gets tighter exactly as your control gets coarser. It is about as small as a game can be while still being one.
Copter Cave is an original, free browser take on the one-button cave-flyer genre, adding a rationed hover stabilizer and a daily seeded run. Play instantly, no download required.