Unity Asset Usage

I know that the assets have to be downloaded through unity but am I allowed to take the assets and use them with a different engine?

 

Asset Store Terms: http://unity3d.com/legal/as_terms

As per this Help article, "you may use the majority of assets from the Unity Store in other engines without limitation".

 

Man, good luck trying to figure those TOS out fully. They've been updated piecemeal so many times that there are parts that seem to directly conflict with each other. For example, section 3.8 says you cannot "copy, sell, license, distribute, transfer, modify, adapt, translate, prepare derivative works from, decompile, reverse engineer, disassemble or otherwise attempt to derive source code from the Unity Asset Store or the Assets", while section 6 says "Except for Services SDKs, END USER may modify Assets." (You could make the argument that 3.8 is referring to CODE only, not things like art assets, but a legal case could be made that a 3D model is nothing more than a set of code interpreted to represent art.)

I think it's good to be aware of the terms, but it's also important to just use common sense. If what you're doing seems like it's violating someone else's property, be that Unity or an Asset Store creator, you shouldn't be doing it and should expect potential legal ramifications. Otherwise, if what you're doing feels like a legitimate use for making a game where all applicable parties have been compensated appropriately for their contributions, carry on. But you're not likely to get any useful legal advice here beyond "Check with a lawyer," since no one wants to put themselves in a position where they may be accountable for giving you the go ahead if you end up getting yourself into trouble.