Close To Done.
Starfire, while being an excellent Tyrian clone, suffers from a few setbacks. Gameplay scales nicely, but the power acquisition curve is a bit fast - putting a bit of money in the hands of the player instantly results in massive upgrades. The upgrades themselves do not appear to be commensurate with level; levels 1 and 2 are a breeze once the controls are mastered, but level 3's boss will have gamers screaming at their computers in rage.
Speaking of the level 3 boss, this is the single most discouraging aspect of the game. His instant kill dash attack cannot be survived even with the best shields and armor, and his ability to fire off lethal shots and then dash into the gap between his ranged shots makes it impossible to dodge at times. Worst of all, the "invulnerability" boost does not make you invulnerable to this attack.
Aside from this one boss, a very solid game. The ability to purchase boss save points, or extra lives, would round it out nicely.