Honestly, this is a great start to a game, but I really feel that it can be improved in a number of ways.
The graphics have a somewhat cartoony feel to them, which is good in and of itself, however the visuals grated on me with their repetition. For example, all of the levels are the same: soldiers hide behind six tanks in the exact same place for the duration of what could possibly have been a two-hour long battle. Some variation, such as different levels with different enemy hiding spots, and perhaps some civilian targets to avoid (classic shooting-gallery/killhouse style) would have been great.
Probably adding a little depth of field to the world wouldn't have hurt either, being a 'sniper' game, and all, there really wasn't much of a sense of scale. The tanks appeared to have been stacked on top of each other; this really could have used some perspective in my opinion. Although, I did notice that enemies scaled down when the levels got further along.
The gameplay mechanics are nothing new; tried and tested Time Crisis style shooting-'em-up. However one major concern of mine is the lack of a reload; I did notice the ammo counter down the bottom, but reloading was instant, which to me defeats the purpose of having it! Perhaps a type of cover mechanic, similar to the aforementioned Time Crisis, making it necessary to take cover to reload in between clips.
And now, the sound. Well.... there isn't any. This made gameplay rather disconcerting, as I couldn't tell when I was being shot at, when I was taking damage, or even when my shots were connecting other than relying on visual feedback. I would say that before all else, sound should be added. Unless it's just me, but my speakers aren't quite *that* broken (although they do like to be from time to time).
All in all, this is a very promising start to a game, and I wish you the best of luck with it! I look forward to seeing what this becomes.