Interesting idea, but it's too chaotic right now.

Also no punishment/reward for dying/winning respectively.

Like the idea, kinda fun to play, however the sword is useless as others have said, too many enemies being spawned for no reason, has a lot of potential but I would consider the game as it is right now as a *very* early beta of a game.

It's pretty fun. I kept dying a lot when the missiles blocked me mid-air until I discovered the double jump. However, the sword is completely useless – there are too many enemies being spawned infinitely, and the sword also completely stops your movement. But the fact that it's procedurally generated is a big plus in terms of replayability, although eventually, you'll have seen all the building elements many times.

I would like it more if there was a goal you had to reach, or at least if the game kept evolving, so there was something more you could 'discover'. Ideally permanently, so you still have access to it even if you die, so there's some semblance of progress.
For example, if you reach '5' (or multiples of 5), a new type of enemy will be added; or a new kind of platforming challenge and from then on, it may appear in levels even if you die.
Or a sword upgrade if you reach 10, making it gradually less useless, culminating in a 'boss fight' as the final unlock.
…anyway, those are just a few ideas which might make the game more interesting, because personally, I reached '9' and felt that I did everything this game has to offer.

You could also add a scoreboard (Newgrounds has one built-in, with a Construct 2 plugin):
http://www.newgrounds.io/get-started/
https://rexrainbow.github.io/C2RexDoc/plugins.md/rex_ngio_scoreboard.html
If players can compete with each other, they'll typically play the game for longer.

In summary, it's fun, it's challenging, the randomness makes it more interesting, but eventually, there's no 'goal' to keep you playing.