It would certainly keep me busy for 6 months. With all the other demands on your time in the final months of your Masters program, you should select the simplest project you can get away with. It has to comprise enough of a challenge to demonstrate your mastery of the subject of your degree, but it doesn't have to add anything to the store of human knowledge - that's for PhDs. Only you and your faculty advisor can decide what's adequate to meet the requirements for your degree, so I'd discuss it with him/her. I know from experience that it's very easy to pick a project that is far too hard to complete in the allotted time, and you really don't want to get into that boat. Keep in mind that, if your school is doing its job properly, you're going to have to submit a project proposal, a schedule, a top level design, a detail design, monthly progress reports, a test plan, test reports, program documentation, and a final report. That's all on top of actually producing a product that works. They all take time that you'd rather spend coding, so please keep that in mind when selecting the scope of the project you propose. The details will kill you. Keep it simple, but make it comprehensive enough to make your advisor happy. Good luck, and congratulations on making it this far! :-D
"A Journey of a Thousand Rest Stops Begins with a Single Movement"