What i know...well... i have played the missions at least twice, modded map/cars/bikes/planes, imported new cars/bikes/planes/boats changing the water level is cool, all city were underwater world and played it online too, it was cool !...and so on
What do u mean ? I modded it myself...for GTA its very easy.
I made big laburynth on the airfield runway and made offroad track and a big jump and modded car to jump over half map... and many more...i cant really remember, it was long time ago...
For the laburynth i wrote vbscript to add perfect lines of fences to create grid.
Then maybe you had mod, where all textures are getting much better, also special effects, shoot sounds, models, well, also atmosphere from GTA IV also taken when you play it, you can't believe it's old San Andreas.