Very cool game, nice action, and nice game feel to it (thought always improvable with some polish).
If you want to continue with the development of the game, I have a few suggestions that might be helpful:
- Add some decorations or texture to the arena, to the background: they can help with making you not feel lost as you move, because when there are no enemies or coins/particles on screen, you cannot really see where and how fast you are moving, but with decorations or patterns on the background you will obviously have a sense of where you are going and how fast you are moving (and also let you better see how much you scale up with each upgrade);
- Lower the difficulty curve at start, since I feel like when the big triangle spawn, they are so fast I always lose (obviously, it's me being not skilled enough for the game, but maybe having a lower difficulty at start and then increasing the difficulty later so the game stays challenging may be a better approach to make players not quit the game after a few instant-death attempts);
- For some visual adjustments, maybe try to see how the game looks if you reduce bloom radius and add or increase the vignette effect a bit (bloom is very high, which can immediately make a programmer-art game look better obviously, but also be too overwhelming if you overuse it... but that's just a matter of personal preferences, if you like the bloom like it is and don't feel like changing it, that's your choice obv)
Nice game overall, nice mechanic and interpretation of the theme