protonscr

NASCAR 25

protonopen appid 3873970Game compatibility - Unofficial
ValveSoftware/Proton#9216 · opened 2025-11-13 by CookiePLMonster · updated 2026-01-12 · 6 comments · github · game page · search this game
CCookiePLMonster 2025-11-13 github

Compatibility Report

  • Name of the game with compatibility issues: NASCAR 25
  • Steam AppID of the game: 3873970

System Information

Steam Deck LCD 256GB

  • Video driver version: Mesa 24.3.4
  • Kernel version: 6.11.11-valve24-2-neptune-611-gfd0dd251480d
  • Proton version: Proton 9.0-4, Proton Experimental

I confirm:

  • [x] that I haven't found an existing compatibility report for this game.
  • [x] that I have checked whether there are updates for my system available.

steam-3873970.log

Symptoms

The game crashes on an illegal instruction when ran on Deck or a PC with Proton. This appears to be due to a bespoke executable encryption solution used by this game either failing to decrypt the executable, or not even attempting (maybe upon detecting Wine/Proton).

On a Windows PC, I confirmed that the crashing address contains valid assembly code, while the "garbage" I crash on when on Deck matches the disassembly of the executable. The game executable contains in-place self-decryption routines as part of the early C++ static initialization, and it appears to be obfuscated, as one would expect. I do not know if the issue arises from an emulation bug, or if the game detects Proton and trips on it.

Reproduction

  1. Run the game.
  2. Observe an instant startup crash.
Ggu3st 2025-11-20 github

With bleeding edge Proton experimental i am still seeing illegal instruction crashes

I have verified game files. I am on a 512GB OLED Deck

Driver: AMD AMD Custom GPU 0932 (radeonsi, vangogh, LLVM 18.1.8, DRM 3.59, 6.11.11-valve24-2-neptune-611-gfd0dd251480d)
Driver Version: 4.6 (Compatibility Profile) Mesa 24.3.4 (git-8d0948917e)
Kernel Version: 6.11.11-valve24-2-neptune-611-gfd0dd251480d

attached is proton log

steam-3873970.log

CCookiePLMonster 2025-11-20 github

The latest official patch for the game also has many people crash on startup on Windows, while my tests were done on a launch version. It's not impossible that those are related, especially since your backtrace looks like a C++ exception was thrown and reached not-yet-decrypted code.

CCookiePLMonster 2025-11-20 github

Replying to https://github.com/ValveSoftware/Proton/issues/9216#issuecomment-3556537398

Today's game patch boots fine for me again, please re-check.

Ggu3st 2025-11-21 github

Confirmed to boot and able to race without issue 👍. I reckon this will be a back-and-forth from patch to patch with whatever obfuscation tech that iRacing/Monster Games chose for the game.

PPremierPrep 2026-01-12 github

I am on a Lenovo Legion Go S running the latest SteamOS and it tries to launch the game and immediately crashes after the steam logo animation. I've tried the latest Proton, Experimental, and Hotfix

Ggu3st 2026-01-12 github

yeah the build that the devs released before xmas broke the game. i've given up on it and just won't buy future iterations or the indycar game as they're likely to be equally hostile.

very bizarre for a game without anticheat

Proton versions