Firstly, the presentation is immaculate for a game made in 48 hours -- it looks and feels like a polished Edmund McMillen game or something. I also think the shotgun as kickback is a great mechanic, though it took me a bit to figure out that that's what the tutorial sign was telling me. This feels like it fits the 2017 jam's "Dual Purpose Mechanic" theme.
But walljumping is kinda icky -- weirdly I can do it when I use my right hand on arrow keys and left hand on space, but when I try to use WASD and space in both my left hand (so that I can use the mouse simultaneously) I just slip and fall. Instead I try to use my shotgun to boost and help me up the wall, but it's a bit frustrating.