From Arnaud Verhille:
DIRTBIKE – Apple II+ 48 K B&W 
Download: https://github.com/habib256/pom2games/releases/tag/dirtbike-1.0
Twist the throttle, pull back on the stick and send your bike flying! 
DIRTBIKE is a free, open-source side-view motocross time trial for the Apple II. Download DIRTBIKE.dsk, boot it on any Apple II+ or later (or in your favourite emulator) and race the clock across 30 tracks – from gentle bumps to monster jumps.
A real physics engine on a 1 MHz 6502
The bike isn’t an animation – it’s simulated. Rear wheel, front wheel and rider are three Verlet mass points tied by the wheelbase and a springy suspension, with gravity, traction, braking and ground contact computed every tick, 30 times a second. 
Lean back and the front wheel lifts; lean forward and it bites into the slope; land crooked and you feel it. Every jump, wheelie and backflip comes out of the physics, not out of a script. 
Smooth and responsive
Silky scrolling: pixel-smooth, double-buffered hi-res at 25–30 frames per second, redrawing only the lines that change.
Analog joystick: the stick sets how far the rider leans — 8 levels each way, with fine control around the balance point to hold a wheelie as long as you dare. Button 0 is the throttle, button 1 the brake.
Keyboard too: arrows (or J / L) to lean, A / Z for full or half throttle, SPACE to brake.
Brakes that feel right: braking cuts the throttle and brings you smoothly to a stop. In the air the brakes only stop the spinning wheel, which gives the bike a small nose-down nudge, just like the real thing.
Tricks, points and records
Long jumps, backflips (1000 × turns² points: a double is worth 4000!) and wheelies all score — but crash before you land and the pending points are gone. 
Best times, scores and initials are saved on the disk in a hall of fame.
Title tune, landing thumps, a flip arpeggio, a fanfare for a new record — on the built-in speaker.
Leave the title alone and the game shows off with attract-mode demos.
Inspiration and credits
DIRTBIKE is inspired by Dirt Bike by Brad Quick on the classic Macintosh — a little gem of physics fun that deserved a ride on the Apple II. 
Now grab the handlebars and go for that triple flip! 
Source code (with AI help) under GPL-3.0.
