I googled Unity, while looking for C# game engines, and it looks quite interesting. Has anyone here used it to make games? If so, opinions?

i used it a few years ago. it is not a c# engine as you would expect. it merely uses a c#(or java or boo) like syntax for scripting. I like how it does some things, and hate how it does others. Thats generally a thing with using engines though.
although, if you don't have your mind set on how you want to engineer your game, you can easily adept on how unity handles things i suppose.

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Long pork is people!

wzl's burrow

So its a editor built around scripting?
Anyway:

1. Is it flexible?
2. Is it fast?
3. Is it relatively easy to learn?

it's a wysiwig editor that is able to live update from your script files

1. yes
2. yes
3. yes

this depends on the effort you put into it though

_________________
Long pork is people!

wzl's burrow