I don't think ideas are actually worth much - it's the actual game made from the idea which is important.
Two game devs can have the exact same idea and come up with completely different games. One might be really fun too, and the other not so much. The idea didn't really decide any of how the game works, what it looks like, if it's fun, etc.
Truer words have never been spoken. Ideas are cheap, it's the execution that will make a difference.
To the OP:
I just bought Construct 2 after playing with the demo for a while. It's a great teaching tool and a great method of quickly prototyping an idea. I am a 14 year industry vet and am the Lead Designer on MechWarrior Online (mwomercs.com). I have the Jr designers using Construct 2 (the free version) to get them moving in terms of game design and disassembling gameplay in order to make sure their ideas of a game have strong core foundations.
That being said:
How about a restaurant game where people come in... your waitress takes orders and you have to cook them with proper timing to get the orders out in a timely manner and not burnt to a crisp! :)
-Paul