Just today I published the unlocker for MadFinger's ShadowGun. This unlocker is a bit different than the other ones, but then again, ShadowGun is not really a racing game, is it?
ShadowGun Unlocker allows you to select which weapons to carry along, and how much ammo you want to have for it: either fill it up to the max, or set it to infinity. In the latter case you also don't have to worry about reloading you weapon; just press fire and keep pressing fire! Apart from that you can also set your resume position (level and checkpoint), so if any checkpoint offends you, just skip to the next one.