it's entirely sandbox...i never liked it all that much, besides just messing around with random things. it's great if you're the creative type that likes to build things, but really beyond that there's not much to do, unless maybe you find some mods or special maps that are designed for objectives or something. overall though it's generally just like anything creative, you're given the tools to invent whatever you want and can do some pretty cool things, but beyond that there's not much to it. think of it like a box of lego without instructions, or a blank canvas for an artist. it's that sort of thing but with a video game as the medium
![Tongue](http://www.rfgeneration.com/forum/Smileys/RFG/tongue.gif)
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