This modular rocket was inspired by the original Nexus Tower rocket from the 2010 massive multiplayer online (MMO) game Lego Universe. It lasted a little over a year, until early 2012 when it was shut down due to not making enough money to make it worth the LEGO group's while.
Anyway, out of this seemingly small game came many modular rockets each with interchangeable cabin, engine, and nose cone sections. (You can see all of them on the LU Wiki, which still exists six years later: legouniverse.wikia.com/wiki/Rocket ) One of these rockets was the Nexus Tower Rocket, which was made available in July 2011 as a ship you could purchase in the game and "fly" to different worlds. ("Flying" was just a vehicle to get from world to world through a cut-scene, no real flying was actually done by the player.)
The build you see here is just an updated version of the original model, which now has weapons to fight off enemies and a boosted engine unit, where once was a single engine there is now two. The intakes are also modified so they would work in real life, with this print on the front of the nose: www.bricklink.com/catalogItem.asp?P=15068pb004
The rear of the ship features a more powerful thrust output, with the upgrade allowing for another whole engine to be added.
As usual, the rocket is made modular style, allowing for many different combinations to be made.
The rocket now sports a canopy, while still allowing a figure to sit inside. (Their is NO figure with the rocket in the LDD file.)