Are facebook games are made by flash or HTML5. Example: Candy crush saga.
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Facebook games can be done in both or even using 3D engines like Unity. You can definitely develop games running in Facebook by using Construct 2 if this is your question.
Lots of modern 2D games are made with unity and not with flash anymore.
With Construct 2 can make games for facebook and type Candy crush saga but with limitations.