This is a fun little game but to echo previous comments;
I found the left / right / down mechanic to be fine early on, but when the game gets faster then I seem to revert to expecting it to work in a more traditional left / right way. Would nice if left/right was an option, even if it were different keys (A / D) for example
Sometimes you can collect a sword and not have chance to use it on any enemies at all (or maybe just 1), sometimes you can get two right next to each other and sometimes you don't see one for an age.
Would be nice to see different collectables. maybe a dagger that lasts for 1 hit, a bow/wand that attacks enemies from a distance, etc etc.
But overall it is a neat little game, plays well and is well made. A few little additions would could really elevate it!