"@Squize&Render, am I under attack ?"

No not you, just what you're saying

The core principle of this competition is for people to learn from others. That's why there's a request for the source code if you want to be eligible for a prize.
If you share your code for the good of the community, great, you've got the chance of a prize almost as a thank you for doing so.
If you don't want to share your code, 'cause you've got one eye on sponsorship, or ads, or making a bigger better game, then ok, but it's hardly in the spirit of the comp. ( And therefore shouldn't really be eligible for a prize ).

Looking at it another way, this worry that anyone will have an idea so good, that they can convey it so well in 4k, the others will be queuing up to take that idea and improve it and therefore make money / take the credit for the original authors idea.
If it's your game, you're going to have a head start in expanding on it over and above the 4k limit with a view to selling it.
If you are going to improve the depth of the game to increase it's earning potential, then to be honest your 4k code isn't going to be the best basis to do that from, you'll be better off starting again, using as3, using oop etc.

Mate, at the end of the day it's a bit of fun, a bit of a challenge to see what we're all capable of with a tight restriction. I'm entering and I'll be open sourcing my code, even though I can't even win a prize ( And I'm paying $50 so someone else can have a prize ) as I think these things are good for the community.

If you think your game may get 810,000 hits in 2 years then don't share the code, ok ?

Squize.