Hydrogen peroxide powered rocket packs fly for around 30 seconds, because they have a specific impulse of around 125, meaning that one pound of propellant can make 125 pound-seconds of thrust, meaning that it takes about two pounds of propellant for every second you are in the air. Mass ratios are low for anything strapped to a human, so the exponential nature of the rocket equation can be safely ignored.

A pretty hot (both literally and figuratively) bipropellant rocket could manage about twice the specific impulse, and you could carry somewhat heavier tanks, but two minutes of flight on a rocket pack is probably about the upper limit with conventional propellants.

However, an actual jet pack that used atmospheric oxygen could have an Isp ten times higher, allowing theoretical flights of fifteen minutes or so. Here, it really is a matter of technical development, since jet engines have thrust to weight ratios too low to make it practical. There is movement on this technical front, but it will still take a while.

John Carmack

I still don't get why game developers feel like they need publishers in this day and age of ubiquitous Internet connections and BitTorrent file distribution

Developers wouldn't use publishers if it didn't cost so much to make a game. A typical AAA title coming out in the next couple years will have a budget of anywhere from $5million to as much as $20million or more. No small independent developer has that kind of cash sitting around. Typically, all the money a developer gets from their previous titles is spent making those titles; 99% of developers never see any royalties.

Because retail is still king Hence developers need publishers.

Actually, you don't need a publisher to get your games on the shelves at retail, you just need a distributor. Of course, most publishers are also distributors.

For Freedom Force versus The Third Reich, we funded the development ourselves, and are self-publishing online, and are using VUG only for distribution onto retail shelves.

[Disclaimer: I work for Irrational Games, but the statements above represent my own opinions and do not in any way represent the opinions of Irrational Games or its constituents]