Playing game without Steam

[Spicy Michael]

So I copied all files from GTA Vice City from the Steam folder in my main hard drive in my computer onto a flashdrive so I can play the game wherever I want to through the flashdrive. I've done this with other games before, but only once with another Steam game (that game being Postal 2). However, when I enter the folders and find the .exe file to start the game, I get the Application error 5:0000065434 and the game won't run. I also understand that this issue has been had with games that aren't on a flashdrive and being run through the Steam application itself. I'm confused, as this method worked just fine for Postal 2. Any ideas?

[Sergeanur]

This game (as well as most R* games on Steam) have special protection that not allow you to run game without Steam. If you want to play without Steam you have to decrypt code section in gta-vc.exe and then find its entry point.