This is a tool-assisted speedrun. For more information, see http://tasvideos.org/3274M.html
Gunstar Heroes (1993) is widely considered to be one of the best action games on the Sega Genesis, but, ironically, was commercially unsuccessful due to poor promotion. It features a variety of melee attacks, as well as 4 basic weapons which can be combined in pairs (making a total of 14 combinations) — all densely packed in a swift and explosion-heavy gameplay spanning over seven uniquely designed stages. The author takes special care to showcase all the moves the game is capable of, using every possible attack and having lots of fun playing around in autoscrolling sections.
This movie is a little under 4 and a half minutes faster than the previous (http://tasvideos.org/945M.html) one due to more aggressive boss fights and a new movement technique. See the author's comments (http://tasvideos.org/5297S.html) for more details.
The encodes for this movie are also slightly larger than usual — this is due to an amount of colors and on-screen motion even the best codecs have problems coping with.