I liked the game, but surely need some works to do on this game. Great job.

The idea was unique and the gameplay was awesome.

My suggestion would be to add some sort of scoring system and it would've been nice to gradually increase the difficulty from level to level.

Do check out my game too.

Hey, just played your game. I think it's a good start but it's definitely lacking some core elements. For example, there doesn't seem to be any sort of win condition - and that's not necessarily a bad thing but there's also no way of tracking your progress. Whether it be a timer, a kill count, or a scoring system I think there needs to be something to encourage you to keep playing. Visually there could definitely be more going on, at least with the background. Right now its just a solid gray background. Even adding in a couple repeating tiled textures would go a long way toward improving the look. The audio, while not bad, does get old quickly. I think a longer music track would have been a better choice as it repeats quite often. Also you should really consider adding in some sound effects both when the player shoots and when the virus gets hit/dies. I hope you're able to implement some of these changes, just a few small  additions will really go a long way toward improving it.