Tool for making Flash games

Question

Good day! I am planning to create a flash game on my own. Is there an opensource tool for making flash games?

Answer 1

Unity 3D is not open source but it's free of charge:
http://unity3d.com/create-games/ (if you like their license)
(there is also a pro version for $ - but maybe the free one is enough for you

Answer 2

You gave almost no info about the type of game you're planning to build, but if you're looking to make a platformer, The Citrus Engine is really great. It's open source now, too.