This was just a delightful little game! It's a nice twist on the overdone "runner" concept, and all 3 of the mechanics you've created (running, swapping, gun) tie in well with one another. My only suggestions are little things, like making it more clear when the player is hit, or having indicators when the player is speeding up (speed up the music or make a super fast running animation for the character), but other than that, it's great! The colors you've chosen for your pallete are great as well. All in all, a fun micro speedrunning game!