Pandemic 3 is one of the most strategic flash games around. You will have to analyze the situation perfectly and create the strongest disease ever known to man. If you know exactly what you're doing, no cure will be strong enough to treat it and you will kill the entire human race.
Unlike most flash games, Pandemic 3 won't make you join the action. You just have to look at the map of the world and figure out how to spread your disease faster and how to make it stronger. If you don't use the right strategy, doctors will develop a cure and the game will be over. However, you can include symptoms which are not that visible and by the time people realize that they are confronting with a powerful disease, they will already be infected. This is a long game and you really have to focus if you want to win. You will get all of the statistics you need for winning the game, but you have to take a look at the upgrades and figure out which one is best for your situation. If you see that doctors are already developing a solution, you can improve drug resistance or if you notice that all airports are closed, you can infiltrate into the water supply. There are hundreds of strategies that can be used and you will have fun trying to find the right one.
Pandemic 3 is one of the most interesting flash games around. You only control it by mouse, but you will get more action than you would from a classic side scrolling game.