the graphics are simple and the bullet shooting is fun, but it is very difficult to actually ride a bullet due to the speeds and sizes and when firing a bullet, because it spawns on top of the player, it makes the player move a little which is not great. the lack of sound is a bit apparent, having any audio at all would make the experience a little nicer. i also think that part of the design is a bit too difficult due to the lack of checkpoints (at least from how far i was able to get past). it made it a little frustrating at times. i also don't see how it relates to the theme of building.
besides that, it was a nice game. with a lot more tweaks and some time spent on it, i think it could end up being a really nice and fun experience. hopefully after the jam some of these issues are ironed out since the concept is really interesting. nice game and cheers!