McGee might not look like much of a runner when you first encounter him, but man, hit him with some magic and that guy can *cook*. Fun game -- I played it a bunch and 72% was my best. Very satisfying shooting animation and sound, I enjoyed the humor of it (love how McGee's clothes go to tatters, e.g.), and most importantly, when I lost I wanted to see if I could do better. Nice job also of making the appearance of the green ghosts not immediately kill you -- they felt very fair. Nice!
Some suggestions for further development that I hope could be helpful: Once McGee hit 59% he was running so fast that I couldn't catch up to him, and hitting him only with shots when he zooms past could only get me so far, given the way the percentage falls over time. You might think about slowing his run back down once he comes back down under the percentage thresholds, or perhaps slowing down the rate at which the percentage falls, or some other balancing adjustment like that. Separately, at times I struggled to control the witch, particularly where I wanted to slow her down or change direction, though perhaps others will have more skill than me!
Nice job with this!