Development topic: http://gtaforums.com/topic/882755-

Introduction:
Potent Tear Gas is a modification for Grand Theft Auto: Vice City utilizing the CLEO Library. In the standard PC version of the game, the tear gas weapon is unavailable and its effect is ineffective if you manage to obtain one. This mod replaces the grenade weapon pickup behind the VCPD HQ with the tear gas and allows the tear gas to be more potent. You can modify the potency of the tear gas by editing SETearGas.dat, a plain text file, and changing the decimal number in line 1. This mod uses the number 5.0 and the base game uses the number 1.0.

Bonus feature: any law enforcers affected by the gas will increase your wanted level. You can toggle the bonus feature off or on by editing SETearGas.dat and changing the number in line 2. Use 0 for off and 1 for on.

Installation:
* Download the mod (click the Download Mod button). If you are unable to open SETearGas.rar, rename the file to SETearGas.zip.
* Download CLEO for Vice City at http://cleo.li/.
* From the CLEO download, copy VC.CLEO.asi into Vice City's folder.
* If CLEO.asi already exists in the folder, you must delete that file.
* From this mod download, place the CLEO folder containing SETearGas.cs and SETearGas.dat into Vice City's folder.
This mod has been tested only on VC v1.00 US.

Video: