After ~six years of intermittent development, Sonic With A Gun has been released earlier this week. Download and boot up your DOS emulator (e.g. DOSBox) for twenty-five main and secret levels of run'n'gun action across seven main zones, five hidden zones, and a number of 3D bonus stages. Detailed graphics, numerous boss battles and other enemies, lots of variety in stage designs, references to Sonic games you've never heard of, and level layouts that have been called better than the original game's.
No prior installation of Jazz Jackrabbit is required in order to play Sonic With A Gun.
6 years of development? "SWAG"? I'm sorry... I really can't take this game seriously. If you did all the art yourself, I am mildly impressed. That is about it. You can't take a classic series, add a gun, and literally call it "Sonic With A Gun."
It's a mod. :) You've heard of, for instance, people remaking Sonic levels in Little Big Planet? This is the same thing in a different game.
Some other examples: Gamesradar.com
People making mods that recreate aspects of Game A in Game B is an old practice. Do things like "Super Mario Doom" or "Doom Raider" equally disturb you?