Repo ↗ · Source README ↗ · Markdown & license bundle
Image reference (original game): Riders Republic · original-game artwork, provided by IGDB. Image rights remain with their respective owners. This illustrates the referenced original game, not the actual visuals of this rewrite or mod.
Source maintainer: OpenRsG · Revision: eae1c84c11a8 · Catalogued: 2026-10-12
Source license: Apache-2.0 · LICENSE · Article: Source README (format adapted)
The source README follows, with formatting adapted for this site and images replaced by source links. Feature, completion and testing claims belong to its authors and have not been independently playtested here. The Traditional Chinese translation was prepared with AI assistance.
RustRepublic
Freestyle mountain-bike and ski physics in Rust + Bevy. Backflips, barrel rolls,
tailwhips, 540 grabs, carving, V-skating, real crashes into a ragdoll. It runs on the
desktop, or in the browser over WebGPU.
[!IMPORTANT]
No game code, and no game needed. Everything in this repository was written from
scratch for this project: physics, skeletons, animation, rendering and camera. It
contains no code, assets, models, animations or data from Riders Republic, and it never
loads any game files. You do not need to own or install the game to build or play it.It is a fan project inspired by Riders Republic and is not affiliated with or endorsed by
Ubisoft. Some poses, body proportions and timings were tuned against measurements taken
from the game’s own videos and animation files on a locally installed copy, the way an
animator studies reference footage. Only our own numbers went into the code, never game data.
Play
cargo run --locked --release
You need Rust 1.88+, a C compiler, Linux X11/Wayland development libraries and a
Vulkan driver. Press F6 to watch the automatic trick showcase, 5 to switch to
skis, 1–4 for the bikes.
In the browser (WebGPU)
scripts/web.sh # builds target/www (index.html + JS + wasm)
Serve target/www over HTTPS or localhost, for example with tailscale serve,
python -m http.server or any static host, and open it in a recent Chrome, Edge or
Safari. You need the wasm32-unknown-unknown target and
wasm-bindgen-cli 0.2.129, the same version as in Cargo.lock. The build is optimized
for speed; wasm-opt (binaryen) runs when found on PATH or under .tools/binaryen/, and
a gzipped copy (about 8.5 MB) is written next to the wasm. The page downloads that copy and
unpacks it in the browser, with a progress bar, so no server compression is needed.
The page opens straight into the looping ski showcase. A ☰ menu (top right) switches
between ski and the four bikes, starts either showcase, picks tricks, and toggles pause,
bones, mesh, key help, touch controls and fullscreen.
- Touch controls (shown on touch screens): a left stick rides (pedal/push, brake,
steer), a right stick leans and flips, and buttons hold jump, sprint/tuck, flip,
trick/grab and both spins, plus wheelie and the manuals on a bike. Touching a control
during a showcase takes over. Reset and camera recenter sit next to the menu. - Portrait: the view widens instead of cropping the sides, and the camera looks down
so the tall screen shows snow rather than sky. - HUD: the panels shrink, and the key help is hidden.
- Camera: drag empty screen with one finger to orbit, pinch to zoom.
What’s in it
Bike: four disciplines (Downhill, Road, Slopestyle, Freeride), each with its own
suspension, power, grip and look.
- Physics: a fixed 120 Hz two-wheel model with pedalling, sprinting, braking,
wheelies and manuals. Each tyre has one grip budget shared by drive, braking and
cornering, so braking hard in a turn slides, and a front tyre that slides for half a
second washes out. At speed you steer by leaning: the bars dip the other way first
(countersteer), then the bike turns with its lean; at walking pace the bars steer
directly. Land a flip on one wheel and you have to balance it with the
arrows, or loop out or go over the bars. - Rotations: flips, barrel rolls and spins are the bike’s actual momentum. There are
no canned rotations, so you can under-rotate and crash. The rider leads them with head,
shoulders and hips. - Tricks: hand, foot and bike tricks combine freely, with left/right variants.
Superman, can-can, nac-nac, tailwhip, barspin, table, X-up, turndown, Euro table,
invert, crankflip and more. - Rider: pedals with hip sway and ankle motion, and leans and flares the knee into
corners. A sprint throws the bike from side to side with the shoulders pulling on the
bars; at top speed the rider drops low. Landings absorb through the arms and legs.
Ski:
- Riding: carving on the ski’s sidecut (radius = sidecut × cos edge angle, so more
edge turns tighter; past the edge grip the turn skids), with angulation and upper/lower-body separation, hockey stops,
snowplow, tuck and switch riding. - Flat ground: V-skating and double poling, with cadence and speed gain tied to each
push. - Air: jumps with a preload crouch and pop, free-rotation spins and flips, and nine
grabs (Mute, Safety, Japan, Tail, Tip, Truck Driver, Daffy, Spread Eagle, Iron Cross). - Landings: wide-stance absorb and a short skid.
- Crashes: a rigid-body skier with human joint ranges and self-collision that keeps
limbs out of each other and the body to within a few millimetres. Joints break past
their strength, bindings release and poles are torn from the fists at high loads, and
the HUD lists what broke.
Both:
- Crashes: a bad landing, a hard impact (too fast into the ground, or fast and
off-angle) or a body strike throws the rider into an articulated ragdoll that keeps
the momentum. Both are rigid capsule limbs with human joint ranges and self-collision on
one shared solver. A bike rider holds on until the wreck pulls harder than hands and
feet can, and drags and shoves the bike while doing so. - Getting up: outside the showcase, once the body comes to rest (or after 3 s) the
rider stands up where they fell, blending back into the riding pose over 0.7 s.
R still returns to the start. - Sound: procedural, no audio files: wind with speed, tyre roll and skid, snow
carve and skid hiss, landing thuds and crash impacts. M mutes. - Landings vary: the body is thrown the way the touchdown came in, with a little
per-landing randomness. - Smooth motion: the rendered pose blends between physics ticks, and every animation
blend is a critically damped spring, so nothing snaps. - Camera: a chase camera follows your direction of travel rather than the spinning
body. Its field of view widens with speed, and it lifts over terrain instead of
clipping into it. - F6 showcase (each loop takes about 3½ minutes):
- Bike: Superman, backflip, 360 X-up, frontflip, backflip Superman, barrel roll,
no hands + no feet, barspin + tailwhip, table, 360 tuck no-hander, frontflip
can-can, barrel roll no-hander. Crashes: nose dive, sideways landing, half barrel,
over-rotated backflip, incomplete flip. - Ski: 360 Mute (slalom), backflip Safety, 540 Japan, frontflip Mute, Daffy,
rodeo Mute (lands switch), backflip Iron cross, 360 Spread eagle (slalom), switch 180 Tip.
Crashes: sideways 270, under-rotated 720, under-rotated backflip, over-rotated backflip,
incomplete front flip.
- Bike: Superman, backflip, 360 X-up, frontflip, backflip Superman, barrel roll,
- Look: one smooth skinned body per rider driven by the solved skeleton (and by the
ragdoll after a crash), procedural snow/dirt grain on the terrain, tyre and ski tracks
that fade over 45 s, SMAA anti-aliasing (plus ambient occlusion on the desktop build)
and an fps / frame-time line in the HUD. - Debug views: F1 skeleton overlay, F2 skeleton-only.
Controls
| Bike | Ski | |
|---|---|---|
| Move | W pedal · S brake · A/D steer · Shift sprint | W skate/double-pole · S plow/hockey stop · A/D carve · Shift tuck |
| Jump | Space hop · Q wheelie · Z/X manuals | Space: hold to crouch, release to jump |
| Air | Arrows flip/roll · E/T spin · Ctrl+arrows strong flip/roll | Arrows flip/roll · E/T spin · Ctrl full flips |
| Tricks | U/I/O pick hand/foot/bike trick · B hold · J/L side | U pick grab · B hold · J/L side |
| Switch | 1–4 discipline · 5 ski | 1–4 back to bike |
| Camera | Right-drag orbit · wheel zoom · C recenter (touch: drag / pinch) | same |
| Other | F6 showcase · R reset · Esc pause · M sound · H help · F1/F2 skeleton views · F3 log state | same |
How it works
| File | Role |
|---|---|
src/bike.rs |
Bike dynamics, suspension, contact, crash detection |
src/animation.rs, src/scene.rs |
Rider animation layers, two-bone IK rig, interpolated rendering |
src/ragdoll.rs, src/rigid.rs |
Bike rider ragdoll on the rigid-body solver shared with the ski ragdoll |
src/audio.rs |
Procedural sound |
src/ski/ |
Skier physics, animation, rig, ragdoll, rendering, showcase |
src/game.rs |
App setup, input, chase camera, HUD |
src/showcase.rs |
Bike F6 script, driven through the normal controls |
The terrain is a white arena: an analytic heightfield with three small jumps and a 32 m
hill with a 7 m kicker onto a landing table. Run the checks with cargo test --locked --bins.
Limits
- Animation is procedural and authored here. It looks closer to the game than it used
to, but it is not the game’s animation and makes no claim of parity. - Collision uses proxy spheres against a heightfield, not a general rigid-body world.
The rider has no self-collision, so extreme tricks can clip. - The browser build is WebGPU only; there is no WebGL fallback.
Design notes, measurements and verification history are in
docs/DEVELOPMENT.md. That file also documents an optional
research tool, rider-assets. It can inspect a local game install’s archive index, but
it is separate from the game here, and the game never runs or needs it.
License
License and provenance
The README and its translation retain Apache-2.0 terms. Changes comprise translation, links and formatting. Editable Markdown, the original README, LICENSE and NOTICE files are included in the linked bundle. This grants no rights to the original games, their assets or trademarks.
LICENSE
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