After a tough battle trying to get a sorry B rank with the help of keybinds on stage 02(S01 went much better) I'm finally ready to post. I like the different speed settings although being a shmup your ship still moves too much even with the lightest of taps at the lowest speed. Good variety of settings especially the background dim. In stage 01 in the part where you descend to the final boss's location, you're able to 'lean' against the wall without destroying your ship and not being able to shoot at all. I'm not sure how you're handling the player's bullet system but it might pose a problem in the future if you decide to include terrain like so. Despite some frustrating elements such as 'secrets' like extra lives spawning outside the playable area and if you kill that specific enemy too soon, it doesn't even spawn(occurred mostly in S02, bikers on highway), burst being frustrating as it doesn't activate instantly as soon as you hit that key, only a bit later(either it's not clearing the bullets within instantly or the activation itself isn't instant) it's still a fun short demo nonetheless. Some other bugs include being able to pickup your preferred weapon type and restarting the level with it instead of being reset for bonus score and sound not working after clearing a stage, and mid-result you restart the level. Quick suggestion to add an option to disable/enable the game pausing if it's not focused, can't take a quick screenshot in fullscreen like this.
Stage 02 seems to differ from using burst at all given all the safe spots available(and you can shoot from them with all 3 weapon types)on boss arenas so I'm not sure it's intended at all.
The bottom green zone is practically an entire safe spot and the 'tank' tends to come close enough to hit once in a while.
And on the S-02 final/stage boss, same thing happens here, mostly on the first phase as the second one requires you to just do one simple loop around the boss once in a while. Also, bomb spam with laser/shotgun is overkill for sure, allows you to mostly skip any and all boss mechanics in practically no time. Ship's size compared to its hitbox is too big as well, please reduce it. Best of luck on your game, you've convinced me to finally pick up Dariusburst.