Tools

100% Checklist

For keeping track of your progress towards 100% completion. (external link)

By Lighnat0rLighnat0r

dxwnd

Tool that lets you play in windowed mode (external link)

By ghotik

OnMission Changer

Supports GTA III / VC / SA. (direct download)

By EarleysEarleys

Quicksave

A program which allows you to easily save anywhere. (external link)

By Lighnat0rLighnat0r

Saves

"SCAM" Instapass Practice Save

Spawn right next to the hospital (direct download)

By Kamiks0320Kamiks0320

100% saves (Caster's route)

Caster's route (direct download)

By GustrbGustrb

Any% saves

Any% saves. A few missions are skipped since they were either chained for an IP/dupe or were not significant enough to warrant its own save. (external link)

By guywithguywith

Practice Save for Bait

Spawn right next to the marker; Glitched Dodo outside ready to go (direct download)

By iguanaiguana

Practice Save for S.A.M.

Spawn right next to the marker; Glitched Dodo outside ready to go (direct download)

By iguanaiguana

Practice Save for The Exchange

Spawn right next to the marker; Glitched Dodo next to the fence ready to go (direct download)

By iguanaiguana

Splits

16x16 radar icons + weapon icons

(direct download)

By Mopsi

GTA III any%

any% Route with Mission Icons (direct download)

By EidgodEidgod

High-res icons

High resolution icons from mission givers etc as used in the 100% checklist. (external link)

By Lighnat0rLighnat0r

Patches

GTA III v1.1 patch

Updates GTA III to v1.1. Fixes a few annoying bugs (direct download)

By Rockstar Games

gta3.set file

For "Cannot find 640x480 video mode" problem, download and put it in \Documents\GTA3 User Files (direct download)

By Rockstar Games

particle.txd fix for steam (black cars fix)

https://drive.google.com/file/d/19N9F5q6c17NmUKq4P8DLTCKfAnklj75K/view (external link)

Skins

In case you deleted the default skins for some reason (direct download)

By Rockstar Games