Similar Games like Star Defender?

[southernhorizons]

I'm not a serious PC gamer, I just like a few casual games to play occasionally. I like Star Defender, and I was wondering if there are any similar games that have the same format but are more like a war game with maybe planes instead of outer space creatures. I like using the mouse to shoot and control my ship, and trying to evade getting shot down with only being able to move side to side.