UNIX-Style Xdelta Patch Maker (USXPM)

USXPM (UNIX-Style Xdelta Patch Maker) is ISXPM-Lite. You lose GUI but you gain speed and efficiency:

Special features

• Primary focus is creation of Steam game patches еliminating the need to compare old and new versions of the game at all by using direct change info from Steamdb game update page or premade changed files list;
• Using fast hybrid compare method (first check file size, only calculate and check CRC if sizes are the same) to compare old and new versions when Steamdb/changed files list is unavailable or when making patch for non-Steam game or non-game data;
• USXPM automatically calculates free space requirements for USXPM parallelizing manual patch applier;
• Runs on Windows and Linux/WINE.

Manual application of ISXPM patches on Windows and Linux

This manual patch applier was originally made to apply ISXPM (Inno Setup XDELTA Patch Maker) game patches. It is extremely useful in a scenario when ISXPM patch mismatches in one or several resulting files and then rolls back whole patch.

How to correct file sizes in rehashed loose files torrent

This article may be no longer relevant after qBittorent implemented file size correction in later versions. 

 

---

It is originally written for Cyberpunk 2077 update using loose file torrent rehash method but may be applied to any torrent.

If you rehash game files using updated torrent, download missing chunks and successfully recheck files in torrent client you may still get the error Cyberpunk 2077 encountered an error caused by corrupted or missing archives

This happens if some files were updated and their size became smaller in newer version of the game but torrent client did not truncate the file to reflect new smaller size. Even if the game data file contains all needed data and torrent rechecks OK Cyberpunk exe will check the size and will exit with the above error! 

You must use torrentcheck utility to find such files and manually delete and redownload them OR correct their sizes (semi)automatically using batch file TRUNCATE_REHASHED_TORRENT.BAT below. 

Create multiple GTA IV instances for downgrade or modding

This article is for modding enthusiasts who want to save disk space while maintaining several copies of GTA IV. It can also be useful to create a single separate copy of game folder for downgrade.

Reducing space taken by GTA IV copy folder 1

General barebone_iv.bat usage. 1

Example usage scenarios. 1

How to make copy for 1.0.0.0 rollback. 1

How to make copy for 1.0.4.0 downgrade with old radio downgrader 1

How to make copy for classic 1.0.7.0 downgrade with official Rockstar Patch 7. 1

How to make copy for simplified 1.0.7.0 express downgrade with ZolikaPatch. 1

Overall space savings. 1

Portable GTA IV on PC

The guide is updated in May 2026 and this method now works for any GTA IV PC version.

1. Preparation for GTA IV Complete Edition 1.2.0.X
2. Preparation for GTA IV 1.0.0.0 - 1.0.8.0
3. Launching your portable game with portableIV.bat script
4. portableIV.bat