skate-3-rust-engine/docs/DIFFICULTY.md

Difficulty selection and parity boundary

Escape offers Easy, Normal and Hardcore. Changes select the native physics-mode index for the next simulation tick, without resetting bodies, the current animation/trick, input history, equipment preferences or the camera. The choice saves to settings/gameplay.json. Missing settings default to Easy. For a test launch, --difficulty easy|normal|hardcore overrides the saved choice.

Data and code evidence

The runtime already contains converted stock collection data in the private assets/private/stock/skater-collections.json. This change uses its inherited physics_mode/easy, normal and hardcore records through the existing typed reader. It does not substitute hand-tuned force, jump or gravity multipliers. The field values below are rounded for readability; the runtime reads the original float bits.

Stock field	Easy	Normal	Hardcore
MaxPushDVStart / MaxPushDVEnd	1.5 / 1.5	0.6 / 0.5	0.5 / 0.25
JumpMinHeight / JumpMaxHeight	1.71 / 1.71	1.33 / 1.71	1.21 / 1.71
JumpHeightOverrideEnabled	true	true	false
MaxAutoBodySpinSpeed	8	8	0.5
EasyBodySpins / PerfectBodyFlips	true / true	false / false	false / false
UnintentionalPumpScalar	1	0.7	0
AutoPushEnabled	true	false	false
GrindLockDist	1.35	0.9	0.15

These are inputs to the recovered calculations, not promises of a particular measured jump height or speed. Source collection SHA-256 identities:

• physics_mode/easy.xml: 4ee489b21c0e8f70616d0bf42f39a32604f3bec6ee5932671be7f9e5b9d6711c
• physics_mode/normal.xml: 6054c99fd49265da916e647574566f8242adbf4f1d3e42bce2d3f8039ba25344
• physics_mode/hardcore.xml: 44008a66b6f275a21e067ee46bf53be2927379904c97bfc5572ebc71f647aa68

Native reference: the user's Skate3Research TU3 memory image research/reverse-engineering/XexDump/default_82000000_011B0000.bin, SHA-256 f4aa113eb541bfba03dbc108cf5ab43f58c965b20fa3b82f9c40938a0ad841c4. Addresses here are Xbox guest addresses, image base 0x82000000. The research generated instruction translation is supporting evidence; no gameplay code or constants were copied from the older clone implementation.

• Player constructor 82DB18A0, variant setup 82DB1B08..82DB1B78: native order Easy=0, Normal=1, Hardcore=2, Motorized=3, Test=4. Only the first three are exposed to the player.
• Actor packet publication 825937EC and PlayerInput 82DB4048: carry the selected index into processed input +2528 and collection reference +2548.
• SurfacePhysics constructor 82D85D08: five surface collections. The existing native selector normalizes surface types according to mode field +60. Ground force settings now follow that processed selection instead of always reading the startup smooth collection.
• Existing gesture recognizer uses its native Hardcore branch for strength response. It now receives the same selection as the physical/animation packet.

Connected runtime settings

Previously, some systems already indexed all five native tables, while ground forces, jump-attribute override and auto-push retained their startup values. Now ground settings are preloaded for all five native modes and all five surfaces. Selection is an immutable shared handle, with no file parsing per tick. Jump-override selection happens after PlayerInput chooses the mode and before Skeleton processes animation attributes. Auto-push reads that same processed mode. Pumping, ground jumps, air spins/flips, wipeout checks and trajectory grind-lock distance already consume indexed tables.

What is not yet full Skate 3 parity

This is mode selection for the implemented native systems, not a claim that the entire game now matches every retail mode. The current world adapter still has NoGrindEdges, and physical grind-state updates remain incomplete. Changing GrindLockDist does not make those missing controllers work.

Six otherwise unused mode fields lie in the grind-state portion of the native layout: +84/+88, +92/+96, +100/+104. Direct instruction inspection finds interpolating consumers at 82D42720, 82D40D60, and 82D41CE8, respectively, using processed scalar +2624. Nearby native diagnostic strings identify grind states. These consumers are observed in the binary; assigning new gameplay semantics to the hashed field names would require more evidence. They have not been replaced by invented assists or declared implemented merely because their data can be read.

No matched retail replay was run for this change, so complete behavioral parity is not established. Remaining unsupported game states are still reported by the existing runtime rather than simulated by substitute behavior.

Validation

All 70 game tests passed with private fixtures enabled. The private integration test switches all three modes during production ticks, checks that mode selection preserves bodies and pose history, and compares all 15 player-mode/surface combinations with the exact stock push, friction and wobble values. Legacy Normal-mode fixtures now initialize both physics and skater as Normal instead of mixing an Easy packet with Normal cached settings.

Run the complete game suite with private assets:

$env:SKATE3_ASSET_ROOT = Join-Path $PWD 'assets'
$env:SKATE3_MOTION_INVENTORY = Join-Path $PWD 'logs/motion-inventory.csv'
$env:SKATE_MAP_TEST_PATH = Join-Path $PWD 'maps/Skate_2_New_San_Vanelona.skate'
cargo test -p skate-game --locked -- --include-ignored