itch.io

This is three days after I've played, so I may miss a few things... But this should sum up ( most of ) your concerns with my first comment:

Bugs:

The sign randomly rises the level count many more times than it should, which makes it unreliable ( it jumps up randomly, e.g. from 0-14 ).

The coins get extremely loud when collecting them consecutively or in large groups.

The shooter ( cannon or whatever you may call it ) shoots many bullets stacked over each other ( which may be intentional ), but my main problem is that it lingers after hitting the floor ( and stacks on-top of each other ), and if it is above a switch platform, it will continue moving afterward ( leading to it catching me off gaurd ).

Eye-strain:

Gray-scale is important when making artwork, especially for a video game ( since people will likely be looking at it for longer ), since it shows the contrast between colors ( making them easier to differentiate for people who are color-blind/have bad vision ).

For long play sessions, it can be hard to focus on the player as the background is as distracting as they are ( in grayscale, the default green player is the same complexion as the background ). This makes the game harder to play for people with bad vision ( a small fix for this is outlines, but it's more important to first get the colors done right ).

The small checkered background when moved also causes eyestrain, since at fast speeds ( while moving rooms ) it causes a stacking effect... This is a little hard to explain, but: When moving a small repeated texture quickly, it begins to appear as if it is slowing down ( instead of moving with all the other objects ), despite the fact it is moving at the same speed, which can cause my eyes to focus on too many things ( as they are moving separately ). ( this one is the least out of the other problems though )

One last thing:

You don't have to update the game if you don't want to, my feedback is just for you to try and evaluate your future work to see how it may be improved.