Could be ALOT better.
much more effort could've been put into this,
For example, you know how the plane didn't moove unless you made it and how the background didn't move? A real plane would continue to fly or else the plane would fall to the ground, and yes I know it's space, but If the plane isn't moving, the jets shouldn't be letting off any flames, smoke, or visable tracings of heat,
Also, the background was very plain and uncreative, turning me off the game more,
some better sound FX could've been added, and you could've also added some sound FX to upgrades, and customised the FX to be more fitting of the situation, and mabye some FX for the plains moving
These are just some suggestions that would change most votes from a 0-2 to a 3-5,
I also was easily able to see that this game was made by a tutorial because of the simplistics of it.
But, if you put more effort into your next game I will happily support you.
Good luck,
~NWP