I've downloaded the trial but when i open it says
Patching version vendetta-1.8.21 to vendetta-1.8.37...
can't open Contents/MacOS/Vendetta! aborting!

what should i do to get it going

Make sure the Vendetta application is NOT still in the Disk Image you downloaded. :)

If you did copy the program & still encounter these problems, try reading:

http://www.vendetta-online.com/x/msgboard/5/19610
http://www.vendetta-online.com/x/msgboard/5/18882

Note particularly that the program may better be installed in:
/Users/{you}/Applications

rather than in "/Applications"

it happened to me too but how do i get it out of disk image

Much the same as with any program for a Mac that does not have an installer --> you drag it off of the disk image to the location where you wish it to reside.

You may need to create an "Applications" folder in your home directory, as recent versions of OS X no longer include it by default.

Um... there has never been an Applications folder inside your Home directory. There has only ever been one Applications folder, by default.

You can drag the Vendetta Application from the disk image anywhere you want, and then double-click the application. You don't need to keep the disk image afterwards.

Point of history: 10 (Public Beta) & 10.0 & 10.1 *did*, by default, include "~/Applications". I do not remember when, after that, it was removed. Presumably it was removed from 10.2 or 10.3.

I grant, however, the core point that "~/Applications" is unlikely to be present unless previously created by the user on any Mac that can run VO.

Could someone PLEASE tell me what the macintosh system requirements are? I am running 10.2.8, and i'ts not doing anything when i press "Play Vendetta" PLEASE help.

where isthe button" play vendetta?"

When you open the updater window and wait for the application to finish the version check/update process, you will notice a greyed-out (inactive) button labeled 'Play Vendetta' in the lower-right corner of the window.

This button will become active once the version check/update process is done, which allows you to click it and thus start the actual game.

HTH

i thought starting VO was easy never had any problems with getting an app off the image with or without installer and using it... i thought it was pretty self explanatory

You can lead a horse to water...