I was asked to do a work plan at work for a simple flash based game, problem is I've never done anything like this, I googled and read about it but just to be 100% sure before I start writing.
Anyways my questions are:
Any good plan arranges the work you need to do around limits in money, time, or equipment. I think a Flash game will share these needs, even one where just a few people do all the art, coding, and test work.
Your plan should list each main task, a ballpark duration, and available work time (probably as a calendar). You can then match each task to available time, taking care to separate any interdependent work: if you need to finish one task, like "configure test system," before starting another, like "run UI tests," don't overlap them.
If you've never planned a project before, I suggest using a spreadsheet (PC-based) or sticky notes (hand-written). List out your available work time and main tasks, then arrange them to "fit" the rough order of tasks.
This 6min video demonstrates sticky note planning: http://www.youtube.com/watch?v=80c-LRRJ0W8
To turn this example into a game schedule, do a second round of sticky planning that adds people and estimated work duration. This creates a calendar of tasks that you can rearrange to meet money, time, or equipment limits mentioned above.
It's not exactly what you ask for, but a gaming specific example by Derek Paxton is found in the forums for Elemental in this post.
If you trust his extensive experience in the industry, it looks like simple templates should be easy to extract from his post, and since you're looking for "a simple flash game" you probably don't need anything overly formalized.
Who, what, where, when, why, and how. Answer those questions and you have a plan. Make it tactical and concrete such that, if you left, someone else can pick up that plan and continue on.
I'm not sure how simple a project a flash game is, but I would suggest you have a quick risk management session. What could go wrong, how are you going to deal with it.
