Info
Best starting character is Fefnir, for his focused fire makes him a great bosskiller. To unlock X you must beat mission 4-2, the one with the gorilla-dragon boss, and then you get X who's the best character in my opinion, mainly because of his bomb that lasts long, covers the whole screen and destroys enemy shots (which is insanely useful against many bosses). There is another secret character, a sort of penguin, with a lot of HP but very slow. you get him by doing "Mission Special" after having defeated the final boss, but this mission is very hard, so be prepared.
Great game, but could have been slightly better by adding more powerups.