I am a big game development fan but I haven't done any commercial work in the past. I have been asked by a non-profit to look at developing a game similar to the award-winning www.playspent.org

They want the following features:

• support 5 scenarios
• mobile isn't important but compatibility with older browsers would be a big bonus
• they want it to be visual and audible
• bonus is to have it easily modifiable
• support 4 languages

I don't have much knowledge of Flash and would rather avoid using it as a solution. I started breaking down the problem into segments that I will need to examine, they are as follows:

• ability to read the game flow from a file that they can produce (xml, etc.)
• db design to store decision tree
• language challenge
• browser compatibility

I am leaning towards an Google app engine/GWT solution but I am not sure what technology is best for this.

I am really hoping to get your opinion/recommendation on my approach and on what technology is best. A special thanks (and beer if you live in Toronto) will be awarded to anyone who can help give me a ballpark estimate on how much such a game should go for. I know it's tough to estimate but any rough figure will help (how much would you charge for building something like playspent.org?)

Thanks in advance