Controls feel great, cool artwork and music. Also nice that you added a story and dialogue, really well-polished game.
However the score system is really bad in my opinion. Losing half of your points upon dying makes it nearly pointless to grab points after all (at least for a below-average player like me)
It would be better to introduce a life system (which you seem to have avoided intentionally) or subtract a fixed amount of points upon death (something between 5000 and 10000 seems like a good fit to me). Cutting points in half means that a failure after a long time of not dying is punished harder than frequent deaths.
I have to agree with the other people that the level design is too monotonous for a that long game.
I feel that it would be fine to end story mode after the first boss.
An easy way to add some variety would be
- add a color tint to the environment graphics
- change music (!)
- maybe some new enemies or also re-color old ones
Of course it would be better to introduce an entirely new surrounding with new mechanics and stuff but I know that this means a shitload of work for the entire team xD
Anyway, still a fun game, I liked it a lot.
Btw: "average session: a few seconds" in the more information paragraph? Is there any secret speedrun technique that I have missed out on? xD