Interesting game, it does bring me way back to good old days of simpler games. Great job getting something playable that looks done at first glance, I especially liked the volume and contrast idea. The controls were definitely very interesting, if I could make a suggestion, personally I like using WSAD and the numpad as well, but I use numbers 4,5, and 6 if needed, it was hard to keep my hand where I felt I needed it when they were on the others. That being said, it wasn't really a problem so just something to consider. I must have picked the slowest guy on there, but increasing your movement speed over time somehow would definitely be a plus, and would help feel like there's some progression.
I liked the sounds, and the graphics, one thing that did seem strange was the grabbing part, but I don't have any suggestions on how you could alter that. All in all great work for just a one person team, it can be challenging, but very rewarding. Keep up the great work!