rush2-xbox 1.2.1 — how to take a N64Recomp game to UWP

This is a recipe, not a game. It describes how to take a title of the N64Recomp + RT64
family to an Xbox Series in Developer Mode, using Rush 2: Extreme Racing USA as the real case.
Nothing of the game is here.

Documentation only. Nothing to rebuild and nothing to reinstall: the build, the appx and every
file of the recipe are the ones in v1.2.0.

What changed: a fault narrower than stated, and a cause that was never tested

The owner, playing on the console, pinned down where the 2049 acceleration platforms actually
misbehave: only in STUNT events. Not in SINGLE RACE, not in CIRCUIT.

That one detail undoes the explanation this repository had been giving. The cause was stated as
upstream's unported 0x10 collision branch — func_800E1F80, left "for a future runtime patch" in
docs/rush2049_research/collision.md. But that branch is what pushes the car in any mode, and
the same document counts 0x10 polygons on race tracks as well: 78 on track 2, 3 on track 3, 4 on
track 5, besides the arenas and the obstacle course. A branch that is simply absent fails
everywhere, not in one menu row.

So the report stands and the cause goes back to not known. Issue #3 now carries both the scope
and the test that would separate the two readings: drive a 2049 race track that has pads and
watch whether they push. If they do, something specific to the stunt arenas is at fault; if they do
not, it was always broken everywhere and STUNT is merely where you notice.

Why that deserves a release of its own. It is the second claim here to be walked back in two
days — the first was the launch time, blamed on the console — and both for the same reason: an
observation was turned into a cause with no test in between. That pattern is more useful to the next
person than either correction is.

If you came for the launch

It is in v1.2.0 and unchanged here: 5–6 minutes down to ~20 s, with no black screen, from two
independent causes — the mipmap addressing modes making RT64 emit a shader that costs ~200 s to
build instead of 0.3 s, and the first frame waiting for an ubershader pipeline that no draw call
ever uses. Both are written up in docs/HOW-IT-WORKS.md, together with how
to find out which pipeline is the expensive one and how to show something on screen while the
shaders are still compiling.

What is in the zip

Everything the v1.2.1 tag contains — 14 files: the five-step build recipe with the reasoning
beside each decision, one patch against RT64's plume (MIT) kept as a record of a dead end, and the
documentation in English and Spanish.

rush2-xbox-1.2.1.zip
SHA-256  47e989ba35ba3f4865b82dff2e2afc949419217026125355915dac6efb3ac9aa

What is still open

The port plays, at 59 FPS, and the owner confirmed this build on an Xbox Series X. Left on the
table: the game never opens the Controller Pak (#5), the acceleration platforms misbehave in
stunt events and nobody knows why yet (#3), a remnant of the sky fault shows as light triangles
in the top-left corner on tight curves (#6), and a playthrough from start to finish is still
untested (#1).

License

MIT, as N64Recomp and RT64 are. Nothing of the game project is here: it publishes no
license. The UWP forks the recipe builds on are worleydl's.

Rush 2: Extreme Racing USA is © Midway. Not affiliated with them, with Microsoft, or with the
authors of N64Recomp, RT64, the game project or the UWP forks. Rights holders:
jajdpmail@gmail.com.