Retro Game Sprite & Logic Prototyper Build #18

Self-contained HTML5 canvas. The physics core mirrors engine.py (22 green tests) one to one, so tuning a slider here is exactly what the tested model does.

Move / AD  ·  Jump Space / W /  ·  Reset R
Tap jump = short hop, hold = full arc (variable-jump cut, like the tests).
Live physics (mirrors engine.py)

x0
y0
vy0
on_groundfalse
tick0
The default values are the exact constants the Python tests assert.
Click/drag to paint a 16×16 player sprite. It becomes the in-game skin.
Palette

No sprite applied yet — your result will appear here. Draw a sprite, then select "Use in game".
The starting sprite is a small cyan runner. Draw your own, then select "Use in game".