Strategic Web-based Educational Game [Comments Needed] Thread

We've been thinking about a change in the age of Educational Games so we thought we should make these kinds of games once in a while so yeah This is still just a very rough idea of the game and we are still planning to edit it.

This approach which we call S.W.E.G. (Strategic Web-based Educational Game) will have the purpose of solving these educational game issues. This approach especially implements strategic style of game instructions and an exciting online multiplayer feature. We will develop a game in which the approach will be tested. The game will tackle about the concepts of the Immune System in Biology. This will allow us to determine whether this approach will make educational games an effective learning material. A much wider scope of the immune system will also be incorporated. In our game, there will be 4 players which should work cooperatively to defeat the infection. The players will be in-charge of the production and control of the immune system. Their goal is to produce varied immune system cells to defeat the infection and eventually heal the wound. The differences of the way bacteria and virus attacks are further emphasized in the game. The player wins when there are no more pathogens and loses if all healthy cells are killed.

The game is about how the immune system works. However, the players will take the role of the immune system to fight off pathogens which has infected the body. The neigboring cells will be infected or destroyed depending on the pathogen the players are fighting. The players need to summon units or immune cells to be used to defend the area against invading pathogens. The player's goal is to heal the wound or to block the passage of the pathogens and to defeat the remaining pathogen while protecting the area so most, if not all, cells will not be infected. The player can summon units from each base and units cannot be summoned easily. There is only 1 base per player given so teamwork is a must. The players have to pay using the game currency which is stem cells to summon specialized units that the player will use to fight those pathogens. Each unit has their own advantage and disadvantages and special abilities which only they can do, making them unique to each other. To win, the player should not let the area be 100% infected and the player will have to defeat all pathogens in that area. If there is a wound, the player should heal that wound so that pathogens will not enter, regaining their numbers gradually. The players lose if the area is 100% infected and the players are overwhelmed by the number of pathogens present. The more the pathogens in the area, the faster the infection meter increase. There are also different pathogens. The higher the level of the pathogen, the faster it is for them to infect the cells in the area and the harder for them to kill.
Map Model:

So we're planning to program this using Flash/Actionscript and will be using the Player.IO service for the servers (Playerio.com).
We need comments and suggestions for this game about the mechanics of the game. And how long would this take for us to finish this kind of game? Btw, the graphics will be in 2D.
Thanks