Kenshi RNG Fix: Solving Fixed Random Seeds via DLL Injection

Problem Background

Kenshi's MOD system produces identical random results (like NPC positions, item drops, etc.) each time a new game is started without changing the MOD list. This is because the game uses a fixed random number seed, causing players to encounter the exact same random events every time they start a new game.

Solution

This tool replaces the game's runtime random number seed through DLL injection to achieve randomization differentiation for each new game.

Technical Implementation

Referencing RE_Kenshi FixRNG's implementation strategy, seed replacement is achieved by hooking MSVCR100 runtime library and game internal functions:

Hook Target	Description
`srand`	MSVCR100 seed replacement (timestamp or custom value)
`rand`	TLS switching between true random / deterministic mode
`randomInt`	Building::selectParts +0x113, integer random
`random` (float)	Building::selectParts +0x26D, float random
`getFoliageRotation`	RVA 0x6CB8A0, foliage rotation random

Seed Replacement Principle

// Use timestamp instead of fixed seed
void srand_hook(unsigned int seed) {
    if (use_custom_seed) {
        original_srand(custom_seed_value);
    } else {
        // Use current timestamp as seed
        original_srand((unsigned int)time(NULL));
    }
}

All 5 hooks are implemented based on fixed offset addresses obtained through reverse engineering.

Usage

Basic Usage

Place KenshiRNGFix.dll and launcher in Kenshi game directory
Run launcher, choose whether to use custom seed
Start game, each new game will produce different random results

Custom Seed

If you need to reproduce specific random results:

[RNG]
use_custom_seed=true
custom_seed=12345

Using the same seed can reproduce consistent random results, useful for testing and sharing.

Verification

Log shows "Full RNG fix active (RE-style)" indicating all hooks are active
Compare NPC positions and item drops after multiple new games to verify randomization
Enable use_custom_seed to reproduce consistent random results with same seed

Limitations

The hooks in this tool depend on specific game version memory offsets:

Only supports Kenshi version 1.0.64
May need to re-adapt offset addresses after game updates
Cannot guarantee compatibility with other DLL injection tools

Relationship with RE_Kenshi

This tool's hook strategy references RE_Kenshi FixRNG's implementation but is provided as a standalone tool without depending on the RE_Kenshi framework.