Tower Defence

Virus-virus-virus, so many of them and they are attacking! Luckily for you, they are digital virus, not real life virus, so they won't harm you. Unluckily for your computer, since they are digital virus, they will definitely want to harm your CPU processes, so do your computer a favor; destroy the attackers at all costs! Before you start, choose the difficulty level that you believe you can handle. Easy means the virus are easier to kill but you don't get any bonus points at the start. Normal means the virus are a little harder to kill but you get 8000 bonus points at the start. Hard means the virus are very tough but you get 18000 bonus points at the start. After you chose the difficulty level, choose the path that you want to defend. the virus will always come from the entry point at the left, follow the path and then attack your CPU through the exit point on the top. After you select the path, you can start the round. As with other tower defense game, click on the tower you want to buy and if you have enough money, you will be able to place the tower on a location you want. Note that you can't place towers on path. Aside of towers, there are also trap items which you must place on path. Some of these trap items are one use only so you should use them where they will make a difference. Still more, there are instant kill weapons which you can buy at high cost but will eliminate visible enemies at once. How long can you hold all the virus?