The annoying part turned out to be getting into the games at all. Nearly every DOS title from that era opens with a sound card prompt, a "press any key," sometimes a full menu before you even reach a pilot name screen. A cabinet has no keyboard, and on a 128x128 screen the menu text can't be read anyway. So each game in the library gets its own scripted boot sequence that has to go all the way into gameplay: car on the grid, plane in the air.

In the library file it's just data. Indianapolis 500, abridged:

"boot_keys": [  { "wait": 3500, "key": "1" },  { "wait": 3500, "key": "enter" },  { "wait": 2500, "key": "enter" },  ...  { "wait": 2500, "key": "esc" },  { "wait": 3000, "key": "enter" }
]

The 1 answers the eXoDOS sound card launcher. The Enters walk through title screens, since most DOS menus open on the item you want. Indy 500 then sits in an attract loop that says PRESS ESCAPE TO DRIVE, and the menu behind it is already on PRACTICE. So Esc, Enter, and you're in the pit lane.

Working these out by hand was slow, so I wrote a small tool, audition.py. It scripts the keys, then takes screenshots in two windows: three with no input, then four while a movement key is held down. The question isn't "did the picture move", because a car waiting on the start line doesn't move and an attract-mode demo moves beautifully. The question is whether the picture answered the controls.

quiet = spread(frames[:len(quiet_at)])    # mean abs pixel change, no input
react = spread(frames[len(quiet_at):])    # same, movement key held

if w >= 640:    verdict = "TEXT"          # still at a DOS prompt
elif react >= MOTION_THRESHOLD and react >= quiet * 2.0:    verdict = "PLAY"          # it answered the controls
elif quiet >= MOTION_THRESHOLD:    verdict = "DEMO"          # busy, but not because of us
else:    verdict = "STATIC"        # menu or title screen

Real output: PLAY Stunts quiet 0.09 held-key 11.34, PLAY Test Drive III quiet 0.00 held-key 32.31, DEMO Dragon's Lair quiet 96.07 held-key 117.81.

It also writes a filmstrip of the samples, and that's where the actual work happened. Look at the screen it got stuck on, add the keys that answer it, run again. Two or three rounds settles most games. Some things it taught me:

• Holding one direction gives false negatives. Commander Keen was standing against scenery, and Jill of the Jungle was behind a door that said YOU NEED A GEM TO PASS. Both scored as dead. Now the probe cycles right, left and up across the hold window.
• Tyrian's Enters opened its Data reader. The sequence has to Esc back out and press Down four times to reach Play Next Level.
• Raptor's pilot registration happily took "ACE" as a name, and then led to mouse-only shareware screens.
• Tyrian still scores DEMO because its background scrolls by itself. I checked that one and Crystal Caves by eye.

Once a sequence worked I tried a faster cadence (1.5 s between Enters instead of 2.5 s). 16 of 18 games still landed in gameplay, so those boot in 18.5 seconds now.

Curating which games belong here, I realized fast that driving and flying games fit the control scheme best. The only inputs on the finished device are the motion sensor and one clumsy button, and "clumsy" is generous: it's the screen itself, so pressing it puts your finger over the picture. Tilt works well as a steering wheel or a flight stick. A held button, a mouse, or anything that wants typing does not work at all.

The current library: 28 titles in the menu, and a demo reel that runs those plus 13 more.

>td >jump

Most boot into gameplay in about 18 seconds. Tyrian takes 50.

Some games got auditioned and cut, and the reasons are their own small catalog. Descent took the longest. Mapped on a timeline: Interplay logo at 8 s, DESCENT at 16 s, ENTER YOUR PILOT NAME at 22 s (pre-filled with "BLECH"), input device at 26 s, main menu at 31 s, difficulty at 36 s. Then a briefing video that never ends under the emulator. I watched it until 165 seconds. Frontier: Elite 2 gets you into the world but needs a mouse to actually launch. LHX Attack Chopper opens on a manual-lookup copy protection quiz ("What is the Service ceiling in meters of the Mil Mi-8 Hip-C?"). Comanche CD wants a serial number. Raptor and Mortal Kombat need a mouse and a coin slot respectively. Mario Andretti's own help screen refuses to take Escape.